mobile

Newbie to rooting.

I'm gonna be exact with what I have.
Stock 4.4.2 (Lollipop available but I don't wanna get stuck in TWRP with an OTA)
TWRP Installed
Rooted G3.
NO, I REPEAT NO CUSTOM ROMS OR FRAMEWORKS.

I'm afraid T Mobile will force me the Lollipop update someday, and if it does, I will always boot into TWRP because TWRP doesn't work with OTA updates.

So... Here is what I want to do... In the easiest way possible.

I want to get TWRP off my phone, unroot my phone, so I can install Official 5.0

OR.... Is there a flashable OFFICIAL Lollipop G3 Zip I can flash using TWRP?

Please be patient with me, I may very well have future questions on this thread. Thanks a lot guys.