“How do I get rid of the white coating on my tongue?”

The white coating could be simple dry mouth. If it goes away by drinking water, remember to drink water more frequently. If it persists with water, it could be some pathology that will need to be treated, like a fungal infection. I would suggest seeing your dentist, an oral surgeon or an oral pathologist for a consult.

It would be very important to review your recent medical and social history to answer that question. For some people it's as simple as a reaction to a new toothpaste or mouthwash which will sometimes cause a sloughing of the lining of the mouth. But this could also be from an overgrowth of organisms such as yeast, sometimes a secondary reaction to taking antibiotics. It's best to have a professional opinion to be sure.