[Q] Manual Update From Cm Installer?

[f1196504]

I installed cm 11 M8 via the CyanogenMod Installer. But since then, had no update for more than half a year.
SNAPSHOT-M12 is currently the latest available update in the cm community.

So, the question is how can I update from the installler build to the community build manually? Do I have to format everything? It will seem like the installer have Unlock and Root the phone already, so I can simply flash the zip file?

The wiki for cm update never mentioned such thing.