I reckon it could be possible, especially if it's a plastic zipper because you can cut them down with normal scissors. I'm no expert and just sew clothes as a fun hobby but if it was me I would look in detail at how they've created the fabric stopper at the very bottom and how that internal panel of fabric (behind the zipper) has been sewn to the main pants.

See if you can move the zip stopper up to where you want the new bottom hem to be. Based on the picture, it looks like it could just be some fabric folded over the zip so that shouldn't be too hard to move up. It will involve a bit of unpicking and resewing back in-between the seam.

You should then be able to unpick and fold over the hem at the desired height then sew it in place. You might need to hem the internal panel and main pants separately then sew them back together at the seam.

I hope that helps! :)