Is there a way to erase all invisible parts in a layer?

[Veidratox]

Heres the drawing

What i need to do is erase all the layer in which the scales arent visible (not gonna explain why, it will take too long)

[Veidratox]

nvm figured something else out

[Veidratox]

NEVERMIND THIS REPLY, HELP ME PLEASE

[Sjaani · Accepted solution]

Are we seeing the area you want to erase or is this how you want the image to end up and there's hidden content which you want removed, but we can't actually see that content anyway?

I'd be looking at using a mask possibly.