According to Noozer :
I recently did some plumbing and ended up bringing the lines for one sink
through the wall too high. I don't want to toss out the shutoffs just
because they are crimped to a pex line.

Can you pull the shutoffs back thru the wall and push out other holes?
That'd probably be easier.

Is it possible to cut off the crimps? Any easy way to do so?

I'll bet there's a tool for this. Short of that, cut the pex
off the shutoffs and see if you can get a beefy pair of side cutters
or bolt cutters to grab the crimp. Or cut it with a metal
cutting wheel on a dremel. Obviously, if you gouge the nipple,
the shutoff is toast.

The bit of pex under the crimp is toast too.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.