On OSM, we map what is on the ground, even what can only been seen from above using aerial imagery.  To denote that something is private, we use something called access tags.  You canr ead more on why deletion is not the answer here:

https://wiki.openstreetmap.org/wiki/Why_we_won%27t_delete_roads_on_private_property

https://wiki.openstreetmap.org/wiki/Tag:access%3Dprivate

https://www.openstreetmap.org/changeset/159394800