How do I recycle iPads?

Do this first:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Read this:

Apple Trade In - Apple

Apple stores should take your iPad for recycling.

If you don’t have one near you, might want to look for a recycling center nearby.

Apple accepts their products for recycling without charge.

Apple Trade In - Apple

The Best Buy and Staples Web sites indicate that most of their stores will accept tablets (such as iPads) in store, for recycling.