What the hell do you mean by "recycle"? If you mean take it to the recycling center when you no longer want it, then no, it doesn't need a windows key. If you mean sell it, again, not needed, though most buyers would never buy a system without the OS already installed.
If you just don't know how to write a proper question and instead wanted to know how to wipe your drive before getting rid of the computer, here's two ways:
1) (not recommended) Just get ubuntu or mint or any other linux livedisk you like, and then wipe the drive using built in software or dedicated wipers (plenty online)
2) Since you're getting rid of the computer, just remove the hard disk and keep it for later use. If the hard disk is already broken, just take a few carpentry nails and nail the disk in several places. No need for additional security measures unless you're using classified information