Give a bench in good condition to a local charity that might use it. Try senior centers, community gardens, youth groups or educational institutions. You may also get a tax deduction for the fair market value of your bench. Contact local organizations, then arrange to drop off the bench directly. This works for any material bench.
Hold a magnet to your metal bench. If the magnet sticks, it's ferrous (containing iron). If the magnet does not stick, the bench is non-ferrous. Recycle either type of metal bench through a municipal recycling program, if available, or by taking the bench to a scrap metal dealer. Dealers offer different prices for ferrous and non-ferrous metal. As dealer rates fluctuate, call to find out what your offers are, then recycle there. Additionally, communities can vary in the types of metal they recycle.
Look for woodworkers, artisans or contractors who may want the wood from your old wooden bench for use in other projects. Give them the bench outright or take it apart, remove the nails and give them the lumber for recycling or reusing.
Inspect a plastic bench to find the number plastic it's made from, then check with your community recycling program to find out if they take that type of plastic. If they do, recycle through your municipal program. If your local program does not accept that type of plastic, identify a plastic hauler who does, then give away your bench for recycling.