In general: If it is a correct merge you should NEVER remove them from the merge stack just because you don't have access to merge, - someone else might have access, and the fact that somebody managed to place it into the stack shows that someone does have access.
Unding a pending merge will always result in a parent conflict for the generation below and very often also a Cannot View Tree error as the result of that when it is a zombie because the privacy protection for "living" profiles kicks inn.
Only in very rare situations we undo valid merges, but then you have to do that for the whole line.