We are using the "Reltio" crosswalk when updating from UI (this is called default crosswalk. Default could be changed in physical configuration). For example, if I add the "Name" attribute (which was created previously from none-Reltio crosswalk e.g. DT_NPI etc) a new crosswalk will be added ("Reltio" as a source and entity URI as a value). Also, it will ignore previous value to make sure that Reltio crosswalk survives.
It is also, not possible to delete a none-Reltio crosswalk from UI (well, you can do this from crosswalk view, but you need clearly specify which particular crosswalk/value you'd like to delete).
This is the reason why pushing the "trash" button could not lead to attribute removal (for entity/relation).