You can actually follow the guide link from Charles-Tim, but I don’t think that actually removes the unconfirmed transaction because as you know an unconfirmed transaction cannot be removed
LoyceV wants to remove the unconfirmed transaction from his wallet file, so that the coin(s) become available and he can make a new transaction.
As I mentioned in my guide in the other thread, you can use the following command to remove the unconfirmed transaction from your wallet file.
wallet.adb.remove_transaction("TXID")