How to revert setting change that caused bootloop? I have an ASUS Zenfone 2 with Cyanogen Mod 13 (not sure the version but it's from may). 

I was looking at privacy settings and accidentally locked "google play service". as soon as I tapped it my phone froze, I waited a minute or 2 and nothing so I held power to reboot, and it just boot looped.

Is there a way to change this setting with out re flashing my phone? I do have TWRP installed.
It should be by using the file manager under TWRP. Navigate to /data/system/ and look fo appops.xml. rename it to appops.xml.bak so you can have a backup and reboot.

PS: as per this post stackoverflow, you might lose also the notifications setting. But most probably those can be reset after boot.