Withdrawals have a two-step confirmation process, the first is the 2FA and the second is the approval link sent via e-mail. If a withdrawal has the status "Awaiting user approval" it means it hasn't been approved yet, and can still be canceled.
If you'd like to cancel an unapproved withdrawal, follow the steps below:
1. Log in to your Exchange account, and go to "History".
2. Find the pending transaction with the "Awaiting user approval" status, and click on "Cancel".
3. Click "Confirm".
4. Your withdrawal has been successfully canceled.
Only unapproved withdrawals can be canceled. Once a withdrawal has been approved, it can no longer be canceled.