PM> Install-Package Spire.XLS

using Spire.Xls;

namespace HideWorksheetsInExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Workbook class
            Workbook workbook = new Workbook();
            //Load an Excel file
            workbook.LoadFromFile("Sample.xlsx");

            //Get the first worksheet
            Worksheet sheet1 = workbook.Worksheets[0];

            //Set the worksheet as hidden
            sheet1.Visibility = WorksheetVisibility.Hidden;

            //Get the second worksheet
            Worksheet sheet2 = workbook.Worksheets[1];

            //Set the worksheet as very hidden
            sheet2.Visibility = WorksheetVisibility.StrongHidden;

            //Save the result file
            workbook.SaveToFile("HideWorksheets.xlsx", ExcelVersion.Version2013);
        }
    }
}

Imports Spire.Xls

Namespace HideWorksheetsInExcel
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Workbook class
            Dim workbook As Workbook = New Workbook()
            'Load an Excel file
            workbook.LoadFromFile("Sample.xlsx")

            'Get the first worksheet
            Dim sheet1 As Worksheet = workbook.Worksheets(0)

            'Set the worksheet as hidden
            sheet1.Visibility = WorksheetVisibility.Hidden

            'Get the second worksheet
            Dim sheet2 As Worksheet = workbook.Worksheets(1)

            'Set the worksheet as very hidden
            sheet2.Visibility = WorksheetVisibility.StrongHidden

            'Save the result file
            workbook.SaveToFile("HideWorksheets.xlsx", ExcelVersion.Version2013)
        End Sub
    End Class
End Namespace

using Spire.Xls;

namespace ShowHiddenWorksheetsInExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Workbook class
            Workbook workbook = new Workbook();
            //Load an Excel file
            workbook.LoadFromFile("HideWorksheets.xlsx");

            //Iterate through all worksheets in the file
            foreach (Worksheet sheet in workbook.Worksheets)
            {
                //Show hidden worksheets
                if (sheet.Visibility == WorksheetVisibility.Hidden)
                {
                    sheet.Visibility = WorksheetVisibility.Visible;
                }
                //Show very hidden worksheets
                else if (sheet.Visibility == WorksheetVisibility.StrongHidden)
                {
                    sheet.Visibility = WorksheetVisibility.Visible;
                }
            }

            //Save the result file
            workbook.SaveToFile("ShowHiddenWorksheets.xlsx", ExcelVersion.Version2013);
        }
    }
}

Imports Spire.Xls

Namespace ShowHiddenWorksheetsInExcel
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Workbook class
            Dim workbook As Workbook = New Workbook()
            'Load an Excel file
            workbook.LoadFromFile("HideWorksheets.xlsx")

            'Iterate through all worksheets in the file
            For Each sheet As Worksheet In workbook.Worksheets
                'Show hidden worksheets
                If sheet.Visibility Is WorksheetVisibility.Hidden Then
                    sheet.Visibility = WorksheetVisibility.Visible
                    'Show very hidden worksheets
                ElseIf sheet.Visibility Is WorksheetVisibility.StrongHidden Then
                    sheet.Visibility = WorksheetVisibility.Visible
                End If
            Next

            'Save the result file
            workbook.SaveToFile("ShowHiddenWorksheets.xlsx", ExcelVersion.Version2013)
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.Presentation

using Spire.Presentation;

namespace SplitPresentationSlide
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create an instance of Presentation class
            Presentation presentation = new Presentation();

            // Load a PowerPoint presentation
            presentation.LoadFromFile("Sample.pptx");

            // Iterate through all slides
            for (int i = 0; i < presentation.Slides.Count; i++)
            {
                // Get a slide
                ISlide slide = presentation.Slides[i];
                // Create a new presentation and remove the default slide
                Presentation newPresentation = new Presentation();
                newPresentation.Slides.RemoveAt(0);
                // Append the slide to the new presentation
                newPresentation.Slides.Append(slide);
                // Save the new presentation
                newPresentation.SaveToFile("output/Presentations/Slide-" + (i +1).ToString() + ".pptx", FileFormat.Pptx2013);
                newPresentation.Dispose();
            }
            presentation.Dispose();
        }
    }
}

using Spire.Presentation;

namespace SplitPresentationSlide
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create an instance of Presentation class
            Presentation presentation = new Presentation();

            // Load the original PowerPoint presentation
            presentation.LoadFromFile("Sample.pptx");

            // Create two new instances of Presentation class
            Presentation presentation1 = new Presentation();
            Presentation presentation2 = new Presentation();

            // Remove the default blank slides
            presentation1.Slides.RemoveAt(0);
            presentation2.Slides.RemoveAt(0);

            // Append specific ranges of slides to the new presentations
            for (int i = 0; i < 3; i++)
            {
                presentation1.Slides.Append(presentation.Slides[i]);
            }
            for (int i = 3; i < presentation.Slides.Count; i++)
            {
                presentation2.Slides.Append(presentation.Slides[i]);
            }

            // Save the new presentation
            presentation1.SaveToFile("output/Presentations/SLideRange1.pptx", FileFormat.Pptx2013);
            presentation2.SaveToFile("output/Presentations/SLideRange2.pptx", FileFormat.Pptx2013);

            presentation1.Dispose();
            presentation2.Dispose();
            presentation.Dispose();
        }
    }
}

using Spire.Presentation;

namespace SplitPresentationSlide
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create an instance of Presentation class
            Presentation presentation = new Presentation();

            // Load a PowerPoint presentation
            presentation.LoadFromFile("Sample.pptx");

            for (int i = 0; i < presentation.SectionList.Count; i++)
            {
                // Get the current section
                Section section = presentation.SectionList[i];
                // Create a new instance of Presentation class and remove the default slide
                Presentation newPresentation = new Presentation();
                newPresentation.Slides.RemoveAt(0);
                // Add a section to the new presentation
                newPresentation.SectionList.Append(section.Name);
                // Get the slides in the section
                ISlide[] slides = section.GetSlides();
                foreach (ISlide slide in slides)
                {
                    // Insert the slide to the new section in the new presentation
                    newPresentation.SectionList[0].Insert(0, slide);
                }
                // Save the new presentation
                newPresentation.SaveToFile("output/Presentations/Section-" + (i + 1).ToString() + ".pptx", FileFormat.Pptx2019);
                newPresentation.Dispose();
            }
            presentation.Dispose();
        }
    }
}