How do we overcome non-competitive inhibition of enzymes?

Yes, it is typically reversible. Eventually that inhibitor will be released. I'm not sure of any ways to overcome non-competitive inhibition. Perhaps if you add a compound which has a high affinity for the inhibitor, so the inhibitor will be sequestered. It would all depend on the amount of enzyme you are looking at. If it is plentiful, then it wouldn't be as much of a problem as one that is not.