The geoprocessing tool "Enable COGO" add the fields as required and the geoprocessing tool "Disable COGO" does not remove those fields. All it does is makes the field not 'required' which means you can delete them.
We are working on a script tool for migrating your existing COGO measurements to the new schema. JCamerano-esristaff
Once Ground to Grid is implemented we will also pursue a tool to recalculate measurements from geometry. Until then you can use python for that.
Thanks,
Amir