Hello,
Based on Microsoft article regarding PolicyDefinitions folder you should :
- Create a new folder with the intended purpose for example PolicyDefinitions-Office2016
- Copy your old admx/adml files in this folder
- Copy your new admx/adml file for office in this folder
- When it's done rename the old PolicyDefinition folder to PolicyDefinitions-WithoutOffice2016
- Rename the new PolicyDefinitions (PolicyDefinitions-Office2016) folder to PolicyDefinitions
- Check if you have any issue
- If not the case move the folder PolicyDefinitions-WithoutOffice2016 out of sysvol and backup it
- Delete the folder PolicyDefinitions-WithoutOffice2016
Regards,