Hiding ribbon except for admin

Scenario:
Client wanted to hide the ribbon from everyone except admin.

Solution:
1) Open your SharePoint master page
2) Add the following style in head section

<style type="text/css">
#s4-ribbonrow { display : none; } 
</style>

3) Now find the start of the "s4-ribbonrow" tag and add following block before this:

<Sharepoint:SPSecurityTrimmedControl ID="SPSecurityTrimmedControl2" runat="server" PermissionsString="AddAndCustomizePages">
    <style type="text/css">
        #s4-ribbonrow { display : block; }
    </script>
</Sharepoint:SPSecurityTrimmedControl>

4) Save the new master page and publish it.

Article:
Similar article ( Thanks nilesh ) Hide ribbon , Hide/Show Codeplex project