If you plan on permanently deleting a client, then you will need to first archive a client. Once you have archived a client, you will see the option to delete the client, by clicking Delete.
A modal will come up asking you to confirm the permanently delete the client and associated information. The Permanently delete button will initially be disabled until you write the clients' name in the input field. Then you can click Delete.
The client will be permanently deleted from your workspace and no other member can access this client again.