The transaction fee is too low. Blockchain transactions are prioritized by fee. Miners first process the ones that pay them the most. This is part of decentralized computing, and not something anyone can directly control.
I like to use etherscan.io/gastracker to get a sense of current prices.
This article will help you clear the pending transaction. other option is to wait for it to fail. time that will take is impossible to guess. Its based on too many other transactions coming into the mempool, which bumps the lowest ones out first.
Here’s some extra info on it: What is gas? Why do transactions take so long? - #4 by sguthrie