How long does augmentin (amoxicillin and clavulanate) remain in the body?

Not long at all: Augmentin gets cleared from the body rapidly, within hours - which is why we have to take it at least 2x a day. Most pharmacy books list a half-life of 1 to 1.5 hours. This assumes of course that you have regular kidney function, or at least close to normal. Usually, if you count '5' half-lives of the medicine, it's considered 'gone' from the system - so within 1 or 2 days I would expect it gone.