None of the above will change the ROM. The only way to change the ROM would be to flash the phone with the other ROM. Find out the product code for the Rom you want, using Navifirm Plus for example.
Download Nokia Data package manager. There's a cooked version which allows you to connect to Nokia servers and download the ROM for RM-821 and the product code you want.
Once you have the correct ROM, use Nokia Care suite to flash that ROM to your phone. Select "No connection", manually open the product (RM-821) and use "Recovery", not "refurbish". As soon as you click "Start", switch off your phone. Once you get the timing right, your phone will be flashed to the new ROM. All further updates will be for that region.
All the softwares mentioned above can be found via a Bing search. PM me if you face any issues.