An incomplete membership is a membership that has been added to one's cart but is currently pending payment.
If you need to delete an incomplete membership, as an admin, to remove said membership from the member's cart, please follow the below steps:
1- From your MEMBERSHIPS menu
2- Filter on 'Incomplete' statuses
3- Search for the member, and open the membership details you would like to remove
4- On the membership details page, scroll down to the 'purchase group' section, and click on the DELETE INCOMPLETE MEMBERSHIP red button