Is it permissible to use sugar wax (halawa) to pluck armpit hair if it is short and cannot be plucked by hand, and is that considered imitation of women?

There is no harm in using nura (a depilatory substance) to remove pubic hair, and this is not considered an imitation of women, as it is not exclusive to them. The predecessors used it, and it is among the characteristics of the fitra (primordial nature) concerning which there is no disagreement among jurists regarding its permissibility.