how to dispose of hard drives

I've got maybe 10 old hard drives. Lots of different makes. Some are in old junk computers.

I want to clean out my closet, and get rid of computers with hard drives, and hard drives not in computers.

I couldn't find a more appropriate forum than this one.

What do I do to ensure that no hard drive has our personal info on it? Can't think of much----except to take a big hammer and destroy all of them.

Does anyone have a better way of doing that?