I have been searching everywhere over the internet for a upgrade document of OBIEE 220.127.116.11.1 to 18.104.22.168.1 but I don't get any reliable one. Can anyone help me by providing a url of a good document ?
Have you tried the docs themselves? The terminology is a bit confusing, since 22.214.171.124 -> 126.96.36.199 is a "patch", not an "upgrade", in FMW parlance.
It's made more confusing because all FMW products (of which OBIEE is one) are covered in a single patch document.