Q: How do I reset or delete Keychain access password?  OS X 9. 4

You can only reset the password if you know the original. Apple did not make a back door to this as it would be  insecure.

Why do you want to start again? If you just want to start again click create new keychain. Then you start from scratch and the old keychain is kept in ~/Library/keychains just incase you remember your password.

PJRS

Try running Keychain First Aid and resetting the original keychain.

Keychain Reset