Q: Cant remember my password to use Installer on my Mac pro

If you mean the administrator's password for the computer then:

Forgot Mac Password? How to Reset Your Mac Password (with or without CD)

Change the Admin Password with Mac OS X Single User Mode

Reset mac mini admin password: Apple Support Communities

If Apple ID passsword

How do I change or recover a forgotten Apple ID Password?

If you've forgotten your Apple ID Password or want to change it, go to My Apple ID and follow the instructions. SeeChanging your Apple ID password if you'd like more information.