yes that the bug your suppose to be to able remove the skill point but only to level since there skills are still learned
I'm a little confused because your sentences don't make 100% to me.
Are you saying that the brown reset books do indeed work but they can not remove a skill below lvl 1 to 'Unlearn' it?
If that is the case are you sure that you don't have any other skills that require it to be known in order for it to be taken away? could you post a screenshot in-game showing this so we can understand it more clearly?