Run Run Reinstall

So I’ve finished the edit of Metropolitan, and I downloaded a surprisingly atmospheric and appropriate piece of art for the cover, and then when I tried to create the cover with Photoshop, Photoshop up and crashed on me. And crashed again. And kept on crashing.
So it’s now to the point where I de-install it, then re-install it. Except that it’s telling me that I have to de-activate it before I can de-install it, and I can’t de-activate it, because in order to de-activate Photoshop, you have to...