How do I go back to stock please? topic

I have had enough of figuring out how to update a risking bricking my phone all the time

I am rooted, with twrp recovery and cm 10.1 rom

How do I get back to stock please? Where I can just do ota updates

Any help really appreciated all this is starting to go over my head

Thank you

Sent from my GT-I9505 using xda app-developers app