Vertical crack on small pinky toe nail. 1 third of it is loose. is it safe to pull off and will it regrow?

I hate that.: By pulling it off, you risk the chance of doing permanent damage to the nail root. This could cause a bigger issue than you already have. Try trimming the nail to a sensible length and applying a tape to hold the free edge down. As the nail grows it MAY resolve. To remove all doubt and have a more precise solution, based on an actual exam, have a foot specialist look at it.