As an Org Admin, you can reset users' passwords by following these steps:
- Log in as Org Admin and then click Manage Users.
- Find the user whose password you need to reset and then click the user's name.
- Scroll to the bottom of the Profile tab and then click Password Issue?
- Select Email user a random password.
- Click Save.
Users can reset their own passwords within their user profile. See Resetting your Password to learn how.