If you send a transaction to Ethereum network with a gas price insufficient for the transaction or code execution, then your transaction will be in the Pending status for a long and indefinite time.
In an attempt to influence the situation, you can generate new and new transactions. However, until the first problematic transaction with insufficient gas price is processed – you can not do anything.
But the solution was found! You need to send a new transaction to the network, using the nonce of pending transaction and a higher gas price than what you used before. The transaction can send nothing – that is, you can send 0 ETH. Go to Etherscan and find your earliest pending transaction. Note the nonce and your from address. Go to https://www.myetherwallet.com and select the offline transaction tab: enter your from address, send 0 ETH to any address of your choosing. For gas price, use a higher gas price than what you used before. 20 gwei should be good. Note: 20 gwei is 20000000000 wei (that’s 9 more zeros after the 20):
Enter the nonce you got from Etherscan, choose Keystore File (UTC / JSON), select your wallet file, enter the password and unlock your wallet.
After that generate transaction and send transaction. It should overwrite your previous one.
Repeat as necessary to overwrite other pending transactions with low gas prices.