Is it permissible to remove underarm hair during Ghusl, or must it be removed before it, and what is the ruling on the prayers performed after that Ghusl?

Removing armpit hair during ghusl (definition) does not affect its validity, because sequential washing (muwalat) in ghusl is not obligatory according to the majority of scholars, even though it is preferable not to interrupt it. If the hair becomes long and prevents water from reaching the skin, then it must be removed for the ghusl and prayer to be valid. Removing armpit and pubic hair and clipping nails are among the acts of fitra (natural disposition) that should not be left for more than forty days, and they should be done as needed.