Closing clears the config in one transaction. There is no withdrawal step, because nothing was ever deposited.
On the overview, open the row menu of the position you want to close.
The confirmation dialog summarizes the position you are about to clear.
One transaction clears the config. No tokens move: they are already in your wallet.
The position moves to the closed list. The allowance stays for your other positions.
This flow is automatically verified on every release.