For System Administrators, resetting the password of another user can be done in a few easy steps.

From any screen within Elements, navigate to the Setup screen by clicking on the gear wheel in the top-right of the browser window and select Setup.  Next, you'll select Users from the navigation menu on the left-hand side of the screen.  Select Users once again from the expanded menu.

From this screen, you'll see the complete list of users for your firm.  Select the name of the user whose password you need to reset.  From the next screen, hit the Reset Password button in the top-middle of the screen.

The user will receive an email from Salesforce giving instructions on setting up their new password.