You can cancel the membership level for a member in the Members tab of WishList Member.
You can click the check box beside their username and then select “Cancel from Level” from the Select an Action drop down.
You can then select the Level you want to cancel from the corresponding drop down that appears and then click the “Go” button.
Note that this will cancel the membership level of that member. It will not cancel any payments that may be tied to that account.
If there is a recurring payment tied to that member account you will also need to cancel the payment at the payment processor.