Is this the stuff with the Blue grid on it?
If it is yep I’ve come across material and it’s a bit of a shock to say the least to see the grid come off and stay on the surface- brown trouser time for me the first time it happened.
The way to get it off is use a mild solvent- something like lighter fluid does the job- if memory serves me right you can get it off with application fluid sprayed on neat- been a long time since I used it so you’d have to give it a test:) The main thing is that you can get it off without doing any damage.
For what it’s worth I found it to be one of those really good idea products that turned out to be a dud in real life- how the heck you are supposed to tape up a long vinyl and get the lines perfectly registered with the base of the vinyl letters turned out to be a task that was just tooooo much aggro.