Delete service added automatically by ZENTYAL

[BrunovonTroba]

I have today migrated config from 3.3 to 3.4
But I am using different that standard port for managing (let's say 777).
After migration i have entry "Zentyal Administration" from old zentyal and "Zentyal Webadmin" from Zentyal 3.4
In this case I can't set HTTP Services to port 777 because it is already taken by old entry from 3.3 - now unused.
The problem is that I can't delete this old entry as it is marked sa system and can't be modified by user
So - is there any way to delete this entry???