add an option to popup

i have a popup menu with some options can be displayed for each word in a richtextbox
VB Code:
Private Sub mnuWord_Click(Index As Integer)
  
   RichTextBox1.SelColor = vbBlue
   RichTextBox1.SelUnderline = True
   RichTextBox1.SelText = mnuWord(Index).Caption + "  " + RichTextBox1.SelText
   RichTextBox3.TextRTF = RichTextBox1.TextRTF
  
End Sub
when user clicked any option it will be displayed in the text after that word as a tag and change the color and make it underlined

what i need to do is adding two more options
1. Delete tag: which will delete the tag of that word if it is exists
2. Delete all tags: which will delete all tags in the text

how can i delete the tags.