AFAIK that stores the data that was overwritten by the restore. So once you have successfully restored and don't need that data anymore it should be safe to remove.

Having said that I am not 100% sure. So I would move it first and test for a day or 2 if you can, just to make 100% sure... But I honestly can't see why it would be a problem so long as you have no need for that old data...