The following will do that, however you should be aware that if the font is hidden it can easily be un-hidden by anyone viewing the document in Word format. Change BMName to the name of the bookmark.
Code:
Private Sub CheckBox1_Click()
ActiveWindow.View.ShowHiddenText = False
If CheckBox1.Value = True And CheckBox2.Value = True Then
ActiveDocument.Bookmarks("BMName").Range.Font.Hidden = True
Else
ActiveDocument.Bookmarks("BMName").Range.Font.Hidden = False
End If
End Sub
Private Sub CheckBox2_Click()
ActiveWindow.View.ShowHiddenText = False
If CheckBox1.Value = True And CheckBox2.Value = True Then
ActiveDocument.Bookmarks("BMName").Range.Font.Hidden = True
Else
ActiveDocument.Bookmarks("BMName").Range.Font.Hidden = False
End If
End Sub