Urine stained bunny

Help!

Poor sammys's tail is saturated in urine stain.

We have recently moved house. he is eating and pooing fine but he isn't using his litter tray like he used too so I'm assuming this because of the move.
Anyway he is doing the toilet outside is litter tray. It looks as if he's pee'd and sat in it

What's the best way to clean him up? We gave him a rub down with a damp cloth but it has made any difference.

Baby wipes and baby shampoo can be useful to just wipe him down. Don't bathe him or submerse him in water and make sure the room is warm when you wipe him down.