Question How to change status ROOTED to UNROOTED on Download Mode ?

this is from G2 anyone can try it on G3 and update us what he did ?
I being told try to delete rct file .

If i flash to other frimware from other contry on the same Model when i got update it will update to the orignal Ver. of where i did buy the device?
if it does can i dod somting to Prevent it to get update to only the contry i did flash it on Purpose?