4 options:
1) Check out and dont tell anyone
2) Go to a store and get one of those drain-solvents to undo the clog, thus draining the urine
3) Syphon the urine-water out of the tub, then call the hotel to come fix the clog.
4) Fill the tub up with water, so that the urine is dilluted and invisible. Then call the hotel saying your bath wont drain.