How can I fix a door that is leaning into my bathroom?
If it's a wooden door, the door leaf could have warped/twisted. Quite often you can (if you have the space e.g. a workbench) cramp the door up so that it is twisted the opposite way, leave it for a few days and then when you release the cramps the door will spring back to a position where it is (substantially) flat.

If the door is already flat, then it may be that it has been hung incorrectly and you would need to recut the hinges most likely.