Worktime roles can be deleted in Worktime > Administration > Worktime roles.
Select the worktime role you want to delete in 'Worktime role' menu and press 'Delete'.
You will then be asked for confirmation to delete the role:
When you press OK, the deletion will be confirmed:
Please note, that when a worktime role is deleted, it will be deleted from all persons assigned to the role before deletion. The users will also lose all permissions granted by that role. Deleted worktime role can not be restored.