I've not found a way in the new ESRI world to unregister a SDE layer. The only option catalogue gives me is to delete it. Does anyone know how to just unregister the layer???
We can't do this for SQL Server or Oracle.
At time of Post - ArcGIS for Desktop 10.3.1
EDIT: Currently ArcGIS for Desktop 10.8.1 (Still have this problem)
EDIT2: ArcGIS Pro 3.2 still doesn't have this feature - idea to fix the issue found at Unregister SDE Table from Catalog (without deletin... - Esri Community
The problem is that the only other option is to delete the table which means all the triggers, data, indexes and EVERYTHING to do with that table is lost. That is a very destructive functionality for an enterprise application.
If this can't be done then why?