While I don't know exactly what the GRIP program did to accomplish the task of creating a 'Hidden Line' view, if it accomplished this by use of View Dependent Edits, there is one of two things which you can try. The easiest, which will not remove any of the view dependent edits is this is how it was done, would be to go to...
View -> Layout -> Replace View...
...and simply select some other named view other than the one you're current working in. If the edits WERE done using View Dependent Edits, they will not be removed, but since they are 'View Dependent' they will only be 'visible' in the view in which they were created, meaning that looking at the model in any other view means that the edits will not be visible and the model will appear as it normally would. Now please do NOT confuse this with 'Orient View' since all that that does is rotate the current view into a new orientation, which of course is much more efficient and is now the recommended manner in which one would change view orientations because it is much faster. However, 'Replace View', which is the way we did this years ago, actually changes the display to a different predefined view which will have it's own settings and options set including any view dependent objects/edits tied to that view.
Now if these are View dependent edits and you would actually like to remove them, you will need to first switch to the Drafting module and without a drawing being displayed, go to...
Edit -> View -> View Dependent Edit...
...and in the second set of options labeled 'Delete Edits', select the last item labeled 'Delete All Edits'. You will be asked to confirm this, but once you do, all view dependent edits will be permanently deleted.
Now if it turns out that the GRIP program used some other technique to editing the display of the Hidden Line model, I would have to see a sample of a model which was edited using the program before I could make any recommendations.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Cypress, CA
To an Engineer, the glass is twice as big as it needs to be.