How do I clear a stuck Bitcoin transaction.The other answers did not help my situation
if the transaction did not use the optional replace-by-fee scheme, then after 14 days it should be dropped from all mempools and the sender would have the coins back.

if the sender is unavilable or uncooperative and you need the transaction to go through, look for miner priority services; they allow you to pay a fee to get the transaction prioritized.