Shaving armpit hairs with a razor

It is permitted, because the object is to remove the hair, whether by plucking, shaving or some other method. Plucking is better, if one can manage it, because the Prophet (peace and blessings of Allah be upon him) said: “The fitrah is five things: circumcision, trimming the moustache, cutting the nails, plucking the armpit hairs and shaving the pubic hairs.” (Agreed upon).