Quick bum bath!
Place a flannel in a sink, get an inch or so of tepid water in the sink.
Stand bunny so rear end is in water and front is either on your arm or your body depending on bunnys size.
Wash around bits, by feel. It will quickly loosen and come off.
May need another person here, place a towel over your front
lift out bunny
towel dry.
Takes me 5 mins tops these days but they are tricky to begin with. Prepare to come out of it a little damp from carrying after you have washed!
Should, in theory, only end up with damp bum and back feet