i have a popup menu with some options can be displayed for each word in a richtextbox

VB Code:
  1. Private Sub mnuWord_Click(Index As Integer)
  2.  
  3.    RichTextBox1.SelColor = vbBlue
  4.    RichTextBox1.SelUnderline = True
  5.    RichTextBox1.SelText = mnuWord(Index).Caption + "  " + RichTextBox1.SelText
  6.    RichTextBox3.TextRTF = RichTextBox1.TextRTF
  7.  
  8. 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.