A couple of ways to do it...if you turn on "annotations" in your model tree, you can see the GD&T at the top of the model tree and you simply select and delete (if you have 100 GD&T items, might not be easy to find).
If you hover you mouse over the GD&T, you will notice in the message window, it always selects the dimension first, so you either right click pick from list and choose the IDx(GTOL) or use the right click query select to select the GD&T and you can then just use the delete key (there will be no right click delete option.
This is all WF5 (and probably earlier) specific, no idea about CREO 1 or 2.
