If an extinguisher is empty, you can simply throw them out with your recycling trash since they no longer contain hazardous materials. You may want to still check with your local recycling company about the best way to recycle the canister. Call fire department if fully/partially charged.
If it turns out you need to replace your fire extinguishers, you can’t simply throw them away because they’re considered hazardous materials. After all, high-pressure chemicals can be very dangerous if mishandled. Here’s what to do with an old, damaged, or expired extinguisher:
How to Safely Dispose of Expired Fire Extinguishers
How to Dispose of a Fire Extinguisher. If a fire extinguisher is deemed unsafe or inoperable in any way, it should be disposed of properly. Because of the chemicals contained inside the cylinder, it cannot simply be thrown away or recycled with other household products. Instead the disposal depends on the condition of the fire extinguisher.
As such, they can’t just be thrown away – you need to do a few things before you toss them out. If the extinguisher is still full: Call your local fire department (non-emergency, obviously) to see if they will take the extinguisher to use for training purposes or to dispose of themselves.
People Also Searches can you throw out fire extinguishers
Disposal Process for Used, Expired Fire Extinguishers Video Answer
Reference:
https://www.usfa.fema.gov/
https://en.wikipedia.org/wiki/Fire_extinguisher