I know that when ATP is more then it inhibits PFK and hence regulate the number of ATP.
This is correct. High levels of ATP cause an inhibitory effect on PFK, specifically brought about by ATP binding to an allosteric site on PFK. By ATP binding to the allosteric site of PFK, the energy state of PFK significantly increases. Illustrated below are the active and allosteric sites of PFK that ATP (and AMP) interact with.
When ATP allosterically binds to PFK, the rate in which it also binds to the active (catalytic) site(s) of PFK drastically decreases (which is due to PFK already having such a high energy state).
But how does PFK reactivates itself? Is it due to removal of ATP from allosteric site that just reconfigures the enzyme back to normal functional state, or does binding of AMP (after ATP removal) does that?
Well, it doesn't reactivate itself! Instead, AMP directly competes with ATP to bind to the allosteric site(s) of PFK. When this occurs, the binding of AMP causes the energy state of PFK to then again lower, which in turn promotes the binding of ATP to the active site(s) of PFK. It is this ongoing ratio of allosteric AMP:ATP binding to PFK that regulates PFK during this stage of glycolysis.
National Center for Biotechnology Information, U.S. National Library of Medicine