This method clears the application manifest and the cached data manifest, and removes any cached data from the document. For more information, see How to: Remove Managed Code Extensions from Documents (2003 System).

The following code example uses the RemoveCustomization method to remove the customization from the specified document. The example first calls the IsCustomized method to determine whether the document has a Visual Studio Tools for Office customization. This example requires a reference to the Microsoft.VisualStudio.Tools.Applications.Runtime assembly, and an Imports (for Visual Basic) or using (for C#) statement for the Microsoft.VisualStudio.Tools.Applications.Runtime namespace at the top of your code file.

Private Shared Sub Remove(ByVal fileName As String)
    If ServerDocument.IsCustomized(fileName) Then
        ServerDocument.RemoveCustomization(fileName)
        MsgBox("The customization has been removed.")
    Else
        MsgBox("The specified document is not " + _
            "customized.")
    End If
End Sub

private static void Remove(string fileName)
{
    if (ServerDocument.IsCustomized(fileName))
    {
        ServerDocument.RemoveCustomization(fileName);
        MessageBox.Show("The customization has been removed.");
    }
    else
    {
        MessageBox.Show("The specified document is not " +
            "customized.");
    }
}

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

Reference