Turn off user customizations via UI
Supported on: At least Windows Server 2008 R2 or Windows 7
Registry
HKCU
software\policies\microsoft\office\16.0\common\toolbars Options
disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean disabletoolbarcustomizationui boolean msoriddisabletoolbarcustomizationuiinfopath boolean disabletoolbarcustomizationui boolean Description
This policy setting can prevent users from customizing both the Quick Access Toolbar and Ribbon through the user interface (UI). If you enable this policy setting, the following UI entry points are turned off: the Quick Access Toolbar and Ribbon tabs in the application's Office Center dialog box, and the Quick Access Toolbar and Ribbon customization options on the right-click menu on the Ribbon. If you disable or do not configure this policy setting, users can customize the Quick Access Toolbar and Ribbon through both the application’s Office Center dialog box, and the right-click menu on the Ribbon.