You are not able to delete those source entries that have a System Code on them as they relate to other functionality within Access Recruitment CRM.
If there is no System Code, you may still be prevented from deleting the entry if it has been used on other records in the system.
You can also Merge Source codes, using Tools ; Merge Suite ; Sources
📌 Note: You cannot merge sources with a system code.
Please talk to you Customer Success Manager or Account Manager if you would like to discuss this further.