First things first, you have to look at the condition of the product in order to make an appropriate decision. You wouldn't sell a ripped piece of clothing so why would you sell broken cabinets? Speaking of clothing, deciding what to do with old materials is much like deciding what to do with your clothing. If you're familiar with the "keep, sell/donate, toss" piles when cleaning out your closet then you should have the exact same formula with the old materials after a remodel. Naturally you most likely can't make physical piles with everything like you can with clothes but you can make a list that'll help you organize what goes in what pile.
Now before you even begin making the piles you should consider whether you can (or want to) reuse items. For instance if you somewhat recently bought a new faucet for the kitchen sink- keep it! Why toss it out when it's in great condition? By reusing (in this case) a faucet, you'd be saving money because you wouldn't have to find a new one and possibly pay the installation service too. Other items that you could potentially reuse aside from faucets are hardware, lighting, appliances, flooring, and maybe even cabinets too. The reason I'm using the words 'potentially' and 'maybe' is due to the fact that not only is this based on your decision but also on the condition of these materials.
Once you make your decision on the materials and have placed them in the "keep, sell/donate, toss" piles now comes the other questions "What do I do?" or "Where do I put them?" Obviously for the materials in the keep pile, that should be an easy answer; same goes for the toss pile. If you're not sure what exactly should be tossed, a general rule is that if there's anything broken and can't be fixed, definitely throw it out.
"What do I do with this now?"
That question applies more to the sell/donate pile of materials. As far as donation goes, there's lots of places that will happily take your materials as long as they're in good condition. For instance places like Habitat for Humanity accept cabinets that no one wants and we actually recommend our clients to go with them. Depending on the material you can sell them. Things you can sell include any fixtures, hardware, appliances, things like that. Things you probably shouldn't sell are any flooring materials and cabinets, it's best to just donate or toss them. Hope this helped!
Til Next Time,