Recycle iMac desktop?

I called a store here in teh USA and they said yes, but I suggest you call the one you would like to use.

Go to this page to find your nearest Apple Authorized Service Provider (AASP) or Apple Authorized Distributor (AAD) --> Find Locations

Before you take it in be sure to prepare it according to this Apple document: What to do before you sell, give away, or trade in your Mac - Apple Support  

If your local does not accept Mac for recycling. Do a Google Search for your local E-Waste Recycler.