In a worst case scenario where your product completely stalls, first try to drop your price significantly and sell through it on Amazon, especially if you still have some organic ranking. If that doesn't work, Amazon's FBA Liquidation Program is your next option where they sell your inventory to liquidators on your behalf, but expect to recover around 5% of your selling price for eligible units, so breaking even is pretty unlikely. You can also do a removal order and take the inventory back, but depending on your product size the removal fees can add up fast and may not be worth it. Either way the longer inventory sits the more storage fees eat into whatever you recover, so the faster you act the better.