How do you clean pee off of a bed?

If it is wet, sop up the excess with a dry towel. (Like when something gets spilled on a carpet.) Mom used to then place a stick/box/something under the sheets (between the mattress and sheets) to allow them to dry during the day. (Otherwise you may end up washing the sheets EVERY DAY when they’re only gonna get peed on again the next night.)
Who, exactly, is the pee-er??

After soaking it up, air the mattress out to dry as long as possible.

While it is drying, go out and buy a waterproof mattress cover.

Maybe some baking soda. I’m no cleaning expert, but maybe you can dust the mattress and then vacuum it up…

@kritiper 25 years ago a 12 year old spent the night. He peed the bed.

@RedDeerGuy1 Mix up some baking soda and water, spray the area to wet it thoroughly, let set a few minutes, then sop up as much moisture as you can with dry towels. Allow the mattress to completely dry, then vacuum the spot with a real good vacuum with a clean bag to get rid of any remaining baking soda. You could also take the mattress out side and REALLY soak the spot. Don’t just dab at the water to sop it up but compress the spot with dry towels to really get down into the mattress. You may have to put dry towels on the underside, too. Leave the mattress outside in the warm sun until dry.

After that, you might want some enzymatic odor eliminator from the pet store.