We had this argument a couple of years ago.  These are not abandoned or disused.  They are illegal and at least 1 goes straight through the habitat of a creature that only exists in to streams in the park.
They only exist because some mountain biker with a battery powered chainsaw created them.  The Parks department would like to un-create them as they are a danger to park users and wildlife.
If I remember correctly, marking them as "abandoned" still shows them on the map and allows OSM users to attempt to reestablish them or use them as shortcuts.
If this is not the case, and abandoned tracks do not show up them I would defer to the judgment of the Parks department.  However, if they are still visible then I am sure that Parks will still delete them.
There are areas of the Dandenongs National Park that are being turned into dust bowls by Mountain Bikers (see area around Way: 1333897093).  These have all been generated a single biker and are destroying a once pristine bush area.  Every one of these tracks shows up on AllTrails and Strava even though they seem to be labelled as abandoned.
Please do not re-instate these illegal tracks.  In fact please help to eradicate them my making sure they are not seen or propagated. 