What you should do is create them as a user, and do not check the Super Admin box. To create a new administrator, login to your admin panel, go to Admin >> Administrator Editor.
Under the Add an Administrator section, you will create a username and password for that user. Click Add.
Once the user is created, click the EDIT button under Permissions, simply uncheck all the options you do not want them to see. This user will only have access to the options that you leave selected. Just save your settings at the bottom, and you are all set.
