Unrooting phone and uninstalling custom recovery on SGH-i537

[Ekuzi]

I've successfully rooted my S4 Active with Kingoroot, but now I want to unroot. i've tried to flash a custom recovery, and I seem to have succeeded, with the phone booting up with the custom message and an unlocked lock logo. However, I'd like to restore my phone to it's stock level. Help please!

 

[Devo7v]

I've successfully rooted my S4 Active with Kingoroot, but now I want to unroot. i've tried to flash a custom recovery, and I seem to have succeeded, with the phone booting up with the custom message and an unlocked lock logo. However, I'd like to restore my phone to it's stock level. Help please!

https://xdaforums.com/galaxy-s4-active/general/guide-update-to-i537-att-firmware-t2835481