As always...Here's another dog training article about teaching the "leave it" cue.
I find this one to be especially useful and important- whether its playing with an item they shouldn't be or trying to bring you a dead squirrel.
(Yes...Riko did do that once several years ago. He was quite proud of his prize and was very offended that I took it out to the field for the coyotes.)
Anyway...Here's how to teach it in parts.