I found that it says that if a nail (or anything?) is majority hanging off already it is considered halachically detached and therefore if the nail is causing pain one can remove it since rabbanan waived derabanans for pain.
If it is considered halchically detached can the nail be removed regardless of the pain?
The Mishnah Berurah (328:96) explains that where the majority of the nail is already hanging off, it is permitted to cut of the nail with one’s hands if the nail is causing the person discomfort, because Chazal were not stringent in this case.
However, if the nail is not causing discomfort, it is not permitted to cut it off.
I remember seeing Rabbi Falk (of Gateshead) ruling that “psychological discomfort” is also included in the definition of “discomfort,” and is sufficient to permit cutting off the fingernail with one’s hands (and not with an instrument) provided that the majority is already off.
This halachah applies to fingernails, and not to skin (Biur Halachah).