Hi ,
As I have understood you , you have the following text in one cell , say A2 :
John Doe: XXX-23-6789
You want the highlighted text to be removed ; if you want this to be done in situ , in the same cell A2 , then you will need to use VBA.
If you don't mind the output in a different cell , you can use the following formula in that cell :
=SUBSTITUTE(A2, "XXX-", "")
This will leave the following text in that cell , where this formula has been entered :
John Doe: 23-6789
Is this what you wanted ? If not , please give more details and post a few worked out examples of both input and output.