Offer them here at reasonable prices preferably with postage included. If that fails to get shot of them you could a) Try Ebay b) Try Gumtree c) Give to charity shop d) Throw them away
I have a cupborad full of old PC parts and a couple of complete PC's. When the cupboard starts to get full I put an add on Gumtree listing what I have and let people know if they are interested to come round and have a rummage. Have also given a few low spec PC's to charity. BUt genrally I keep things. You never know when you or a friend might need something.
I take from HDD out and then offering them to friends & family etc.
Local charity normally takes old spares if it have any.
But no one seems to want my old x4CDRW drive for some reason!!!
I am using my old system box as a burner for making "chicken bar b q"...... lol
I put out all the parts including processor from my PC system box and fill it with coals to make "bar b q" .
I have tried three times to give away a 17" Dell CRT monitor on the local Freegle site. No takers at all, guess they must be too rich round here.
I have built pc's out of old bits and given them away and given parts away and sold a few bits and bobs. Modern folk are just not interested in making do and codjing up bits to work anymore. Seems that there is no app available that will do that.