I have figured it out by using below code:
Sub RemoveManualListNumber()
Dim strInitialPar As String
Dim intSpace As Integer, intTab As Integer
Dim strFinalPar As String
Dim iPar
For iPar = 1 To ActiveDocument.Paragraphs.Count
strInitialPar = ActiveDocument.Paragraphs(iPar).Range.Text
intSpace = InStr(1, strInitialPar, " ")
intTab = InStr(1, strInitialPar, Chr(9))
Debug.Print "Paragraph " & iPar & ": " & "Index space = " & intSpace & ", Index tab = " & intTab
If intTab > 0 And intTab < intSpace Then
strFinalPar = Right(strInitialPar, Len(strInitialPar) - intTab)
Else
strFinalPar = Right(strInitialPar, Len(strInitialPar) - intSpace)
End If
ActiveDocument.Paragraphs(iPar).Range.Text = strFinalPar
Next iPar
End sub