A succubus can take the form of anything imaginable. As for whether something of her nature can be raped? Yes...and no. If by human hands, no since they lack the strength and/or ability. Now at the hands of another demon, it's well possible.
Uhm, according to folk lore, succubi assume the form of the perfect woman of their victim. So you'd never actually know what a succubus really looks like.
Plus, according to folklore they're ugly as hell when they aren't assuming a form. So if they didn't want to have sex you would be trying to rape something hideous. kekeke
Then this must not be a succubus because I can't imagine a demon that lets something or someone break its horns off. Btw, is this even the whole picture? It's poorly centered and it looks like a sample of the whole thing....