Just to let you know, you can only do these things if you are an account administrator or above.
On the Home page, click on the settings icon. From there click on account. Click on the people tab.
You should have a list of users you have created on the people tab. Next to each name is a number of icons. You will need to click on. You will then be in the profile of the user.
If you click on the section of role, you will be given the option to change the role of that user.
There are two options in this menu, either standard user or administrator.
When you have made the change, save changes.