Blocking the access of a user is an option the merchant can use to temporarily deny a user the rights they have been given and to prevent them from operating with the account. Until unblocked, the user will show under Blocked users. At a later stage, the merchant can decide to reverse the action or delete the user altogether.
Removing account access is permanent and cannot be reversed. If a user is already deleted, they should be added again as a new user, following the process from the start.