In researching how to recycle a car seat, I’ve learned that it is quite the process. You can look for a local recycler that will accept it, but with new regulations from China, these programs are now rare. Sometimes, the most reasonable option is to throw it away. If you are doing so, first cut the straps.
By simply tossing a car seat out, you run the risk of another family snagging it. And expired car seats should not be used. Materials wear down, standards change and models are only safety-tested for a certain lifespan. So before putting it in the garbage, grab a pair of scissors and cut the harness straps, top tether straps and LATCH straps. You should also do this with any car seat that has been in an accident, even a fender-bender.