No, you should not use your air purifier in the bathroom after a shower. This is a safety issue. Using it in a wet environment like a bathroom, or any place with high temperature and humidity, is dangerous.
Moisture can damage the electrical components, cause a short circuit, or create a shock hazard. You should always keep the purifier in a dry, stable location on a level surface. If you need to clean the air after a shower, ventilate the room first, then use the purifier in an adjacent dry area.
Heads up: Also avoid using it in rooms where insecticides have been sprayed recently. Ventilate thoroughly first, as chemical residues can get pulled in and released back out, which can be dangerous.