I don’t think that Rumpel was upset that he killed a human being, but just that it was the old guy that he knew and that he was tricked. I also don’t think that Rumpel now wants to give up his power. I think there might have been a point where he did, but i don’t think that when it first happened Rumpel wanted to give up the power and i don’t think at the time of Belle he wanted to. It is possible that something has changed, but just based on what we have seen that doesn’t seem to be the case.