Recycling an old iMac at an Apple Store
Can I drop off and old iMac at an Apple Store to be recycled?
I'd call first. What individual stores can do often varies with countries or regions.
Your convenience may depend on the store's location and type. If in a mall, you'll be schlepping an awkwardly-shaped computer across a parking lot and through the Mall.
Our closest Apple Store is 100 miles way but we are in that city 5-6 times a year. Even though that Apple Store is a storefront version, it's on a busy downtown street with little to no parking out front. The closest parking garage is in the same block but on the other side of a downtown mall, a 10-15 minute walk.
As a result, I use Staples. There is a store less than 15 minutes from our house, and their acceptance policy is very liberal. It is listed here: https://www.staples.com/stores/recycling
Other office "superstores" may also offer recycling. So you may have options beyond Apple that are more convenient.