After you logged into your account in Ebriza account, go to Account Settings and to the section Users.
All active users will appear with green.
Select the user you want to deactivate and click on Permissions.
From here a new window will open, where you can deactivate the user.
Don't forget to Save the changes.
In order to delete a user, click on the three dots next to permissions. This will open an option menu with the "Delete" button.