The issue of dismissal is a local, legal issue which you'll have to take up with the appropriate overseeing authority.
A bigger picture question, however, is why one would put one's self in this position?
Don't buy alcohol in uniform. Don't smell of alcohol in uniform, even residual alcohol. Don't drink unless it's identifiable, when in uniform.
There's a lot to be said for avoiding even the very appearance of evil, so the saying goes. It's well heeded.