As a G Suite admin you will see shared drives (Typically called Untitled Shared Drive) pop up in the admin console.
To delete them, add yourself as a Manager.
Then find it in the list of shared drives in your browser.
Right-click the drive and choose Delete.
Confirm it has been deleted by looking at it in the console. All options should be greyed out except restore. The drive will disappear after 30 days.