What can I use to safely remove stains from my pet dog's (poodle) hair?

What kind of stains??

A whitening shampoo may help. You may have to clip the hair off, or you may have to let the stain fade. Depends.

Tear stains? Try something called Eye Envy or Angel Eyes.

What can I use to safely remove stains from my pet dog's (poodle) hair?

If your dog is white there are special white dog stain removers out there in shampoo form.

What can I use to safely remove stains from my pet dog's (poodle) hair?

What kind of stain? Please provide more information.