I get that actually. Sometimes I forget there’s no undo button and yeah it’s frustrating when it’s still there. You don’t need to do a whole drawing every time, small doodles are what unwinding on stress is for as well and doodles don’t need to be perfect just draw whatever comes to mind. Also some advice when you start a drawing go over the paper lightly with a pencil so it’ll be more faint and maybe even completely gone when erased. We all feel like this at times and it’s okay dude.