PM> Install-Package Spire.XLS

using Spire.Xls;
using System.Linq;

namespace RemoveDuplicateRows
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Workbook instance
            Workbook workbook = new Workbook();

            //Load a sample Excel document
            workbook.LoadFromFile("Test.xlsx");

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

            //Specify the cell range where duplicate records need to be deleted
            var range = sheet.Range["A1:A" + sheet.LastRow];

            //Get the duplicate row numbers
            var duplicatedRows = range.Rows
                   .GroupBy(x => x.Columns[0].DisplayedText)
                   .Where(x => x.Count() > 1)
                   .SelectMany(x => x.Skip(1))
                   .Select(x => x.Columns[0].Row)
                   .ToList();

            //Remove the duplicate rows        
            for (int i = 0; i < duplicatedRows.Count; i++)
            {
                sheet.DeleteRow(duplicatedRows[i] - i);
            }

            //Save the result document
            workbook.SaveToFile("RemoveDuplicateRows.xlsx");
        }
    }
}

Imports Spire.XLS
Imports System.Linq

Namespace RemoveDuplicateRows
    Class Program
        Private Shared Sub Main(ByVal args() As String)
            'Create a Workbook instance
            Dim workbook As Workbook = New Workbook

            'Load a sample Excel document
            workbook.LoadFromFile("Test.xlsx")

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

            'Specify the cell range where duplicate records need to be deleted
            Dim range = sheet.Range(("A1:A" + sheet.LastRow))

            'Get the duplicate row numbers
            Dim duplicatedRows = range.Rows.GroupBy(Function(x) x.Columns(0).DisplayedText).Where(Function(x) x.Count() > 1).SelectMany(Function(x) x.Skip(1)).[Select](Function(x) x.Columns(0).Row).ToList()

            'Remove the duplicate rows        
            Dim i As Integer = 0
            Do While (i < duplicatedRows.Count)
                sheet.DeleteRow((duplicatedRows(i) - i))
                i = (i + 1)
            Loop

            'Save the result document
            workbook.SaveToFile("RemoveDuplicateRows.xlsx")
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.Presentation

using Spire.Presentation;
using System;

namespace AddDigitalSignature
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Presentation instance
            Presentation ppt = new Presentation();
			
	    //Load a PowerPoint document
            ppt.LoadFromFile("Input.pptx");

            //Add a digital signature
            ppt.AddDigitalSignature("gary.pfx", "e-iceblue", "test", DateTime.Now);

            //Save the result document
            ppt.SaveToFile("AddDigitalSignature_result.pptx", FileFormat.Pptx2010);
            System.Diagnostics.Process.Start("AddDigitalSignature_result.pptx");

            //Dispose
            ppt.Dispose();			
        }
    }
}

Imports Spire.Presentation
Imports System

Namespace AddDigitalSignature
    Class Program
        Private Shared Sub Main(ByVal args As String())
            'Load a ppt document
            Dim ppt As Presentation = New Presentation()
            ppt.LoadFromFile("Input.pptx")
	    'Add a digital signature
            ppt.AddDigitalSignature("gary.pfx", "e-iceblue", "test", Date.Now)
	    'Save the document
            ppt.SaveToFile("AddDigitalSignature.pptx", FileFormat.Pptx2013)
	    'Dispose
	    ppt.Dispose()		
        End Sub
    End Class
End Namespace

using Spire.Presentation;

namespace RemoveDigitalSignature
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Presentation instance
            Presentation ppt = new Presentation();

            //Load a PowerPoint document 
            ppt.LoadFromFile("AddDigitalSignature.pptx");

            //Detect if the document is digitally signed
            if (ppt.IsDigitallySigned == true)
            {
                //Remove all digital signatures
                ppt.RemoveAllDigitalSignatures();
            }

            //Save the result document
            ppt.SaveToFile("RemoveDigitalSignature.pptx", FileFormat.Pptx2013);

        }
    }
}

Imports Spire.Presentation

Namespace RemoveDigitalSignature
    Class Program
        Private Shared Sub Main(ByVal args() As String)
            'Create a Presentation instance
            Dim ppt As Presentation = New Presentation

            'Load a PowerPoint document 
            ppt.LoadFromFile("AddDigitalSignature.pptx")

            'Detect if the document is digitally signed
            If (ppt.IsDigitallySigned = True) Then

            'Remove all digital signatures
            ppt.RemoveAllDigitalSignatures()
            End If

            'Save the result document
            ppt.SaveToFile("RemoveDigitalSignature.pptx", FileFormat.Pptx2013)
        End Sub
    End Class
End Namespace