Default [Q] Samsung galaxy s3 i747M unroot on 4.3

Hi, im new on XDA but have quite a lot experience whit phone.
I tryed to root my samsaung galaxy s3 from Rogers (same as att) i747M whit CF-Auto root (im on android 4.3 jellybean).
I did it my phone is still working. I didnt flash a new recovery or anything.
Now i woudlike to remove root finally.
*the counter of the new Knox is set now to 0X1 but personnally i dont really mind.
The problem is that i woudlike to remove the root. I dont whant to downgrade i like 4.3 jellybean. (Anyway Att s3 cant be downgraded it will result to a soft brick)
I dont know how to remove the root and i woudlike to learn how to do it on my Samsung galaxy s3.
Thanks

(i was wondering about if i download the 4.3 stock Rom and i flash it will odin will it brick even if its on the same bootloader? because thats not downgrading...)
Thank you in advance for helping me out fast!