Skull bash and meteor beam both raise a stat on the waiting turn so does power herb remove it or not
No. It boosts the stat, then the power herb activates and uses the move. The stat boost stays.
Source: https://replay.pokemonshowdown.com/gen8ubers-1164856740-3e19ykb0ej0r3iq7pwptf0mweb7ecp4pw (And as you can see, it is quite effective)