Did not installed a Recovery before ROOT

Hey guys, this is my first post here, so if i intrude or break any rules, I'm sorry in advance.

I got a Zenfone 2 and rooted it by following the One-click ROOT method from here:
http://forum.xda-developers.com/zenf...-easy-t3114003

I did not install any CWM/TWRP on my phone since the instructions on the thread did not specify it. After the ROOT process I updated SuperSU using the "Normal" option and not the "TWRP/CWM" option

Everything worked perfectly, and then i installed Xposed Module from here:
http://forum.xda-developers.com/xpos...fones-t2983589

After a while i received a notification that an OTA is available so i decided to uninstall Xposed and Full UNROOT by using Super SU. After all of the process were done, i check my phone via the Root Checker app, it said that "ROOT Access is not properly installed". After that i boot into Recovery Mode, cleaned everything, checked again with the app, but it still says "ROOT Access is not properly installed". What do i do to completely remove the ROOT Access? Do i need a Custom Recovery like CWM/TWRP for that?

P.S. I already flashed the latest official frimware from ASUS using ADB so now my phone is up to date, but after i checked, the ROOT Access is still there and it's still not properly installed, so decided to ROOT it again until i find a way to completely remove it.