Cancelling a transaction : Custom nonce
1. Enable Custom Nonce in advanced settings of your OneKey wallet: 
2. Send a new transaction. In the new transaction, you can send TO yourself, meaning your OneKey public address. Then in the nonce set it to the last transaction nonce that is still pending: 
ps：
1. set the gas higher (to what is recommended on https://ethgasstation.info/).
2. ETH amount can be left at 0.
In order to prevent double spending problems and repeated transactions, every transaction on Ethereum has a Nonce value.
The transaction starts with Nonce being 0, and the Nonce of the next transaction is equal to the Nonce+1 of the previous transaction.
Ethereum packages transactions in the order of Nonce, and the next transaction must wait for the completion of the previous transaction before proceeding.
Use the same Nonce as the stuck transaction to send yourself a 0 ETH transaction. The 0 ETH transaction will be packaged first. Due to the repeated Nonce, the stuck transaction will be cancelled.
