I have a problem with my phone wanting to update to ZV6

So about 3 months ago when i got my phone i used titanium backup to freeze my system update app, and i then rooted my phone. Today i wake up and my phone tells me it wants to update to ZV6 from ZV5, now i know that if i update my phone being rooted that i risk bricking it. So my question is can i use the ZV5 restore to reset my phone even though if i reboot the phone it might update or how should i go about reseting my phone to stock before updating it, or how should i go about unrooting so that it does not update on me and brick my phone. Any help will be much appreciated