Deleting core data version xcdatamodel files

Deleting the old models means you cannot migrate any existing data stores. I assume you're ok with that given your statement about data loss. If you want to start fresh, you can take the current xcdatamodel, copy it somewhere else (e.g. your Desktop), then delete the xcdatamodeld folder. At this point, you can drag your saved xcdatamodel back into Xcode and re-add it as a non-versioned file.