I've read before in this topic you can flash stock firmware over the rooted one, but check first, please!
My phone was rooted and twrp installed, but has not latest firmware.
For latest firmware:
1. I downloaded to ext sd card latest firmware: "UL-ASUS_Z00E-WW-13.1010.1612.53-user".
2. Restart in twrp and install firmware.zip and wiped cache and Dalv...
Update is OTA (over the air). Old firmware (no root) was Lollipop; over the air arrived android Marshmallow. After update, I followed the tutorial from first page using Magisk (not superSU) and now yt3 x90l with 2GB RAM own MM with root.
Yes, my phone has WW_188.8.131.52_20161026 version and it is rooted with tutorial from first page.