What to do with the new parts on an old bike I want to dump?
Dumping is possible, but dump it somewhere useful rather than into a landfill.

I suggest a bicycle cooperative, who will use your parts to refurb other bikes, or if the parts are completely unserviceable then they will separate and recycle the different metals

A quick google returns these coops in New York, in no order:


http://times-up.org/bike-co-op
https://cargobikecollective.wordpress.com
http://bikecoop.nyc
https://www.bike.nyc/recycleabicycle/


These are not retail shops, instead they are workspaces or groups where riders work on their own or donation bikes.  The coops may be attached to a shop but are separate entities.

Different coops have different "eligibility" parameters for assistance, so it may be worth reading their websites before selecting one.

I know of one coop that limited their "zone" to 5 square kilometres (a city of ~100 square km)  and excluded assisting anyone who owned a car.

Another thought is that a donation to a registered charity may have tax benefits for you.