The file that stores the ribbon customization is with Extension .officeUI.

The file that stores the ribbon customization is with Extension .officeUI.

 The location you can find the file is :

C:\Users\<username>\AppData\Local\Microsoft\Office

The name of the file will be same as that of the application:

Outlook : olkexplorer.officeUI

Excel : Excel.officeUI

Word : Word.Office UI

PowerPoint: powerpoint.officeUI   and similarly the rest of the applications.