If you have a transaction that is pending, you can attempt to cancel it easily within the app!
The way this work is the wallet sends another transaction that is valueless to replace the original transaction. Keep in mind there is still a chance the original transaction might go through.
Step 1: Navigate to the transaction history screen and tap on the pending transaction
Step 2: Select the "Cancel" option
Step 3: Confirm by tapping "Attempt Cancellation"