There's a split here: support can disconnect and delete a store for you — send them the store name (and region) and they'll remove it and confirm in the chat — but the support team does not delete Easync accounts.
If you want to fully close your Easync account (for example because you're handing it to someone else), you do that yourself from Account Settings (my.easync.io/account/settings).
So ask support for store removal, but delete the account on your own side.