WishList Member: Remove/Cancel member

Hello,
I have a workflow setup using Pabbly webhook (from Digistore24) to Wordpress WishList Member plugin.
When a customer cancels his membership (without trial), the webhook catches the "on_rebill_cancelled" event. Then I want the member to be removed or cancelled from the membership level in WishList.

Both options are available, but both don't seem to have any effect (member is still in the level).
Please see the attached images for the responses: HTML Status 415
I'm not sure what these responses mean and how to proceed from here.

Thank you

Hey @Lawyal

Kindly use the "Wishlist Member: Search Member via Email" action step first to retire the member's Id which will be passed in the "Member Id" Field in terms to Remove/Cancel the member.

Thank you @Supreme, that was very helpful!