I have forgotten my iCloud username and password and need to turn Find My iPhone off. What can I do?
If you have Find My iPhone turned in, then you are signed into iCloud. Go to Settings > iCloud. At the top it will have a name and iCloud ID. Write down the icloud ID (it may be one of your non-apple email addresses) then click on that and it will ask for the for the password. If you cannot remember it, click the Forgot Apple ID or Password link in blue. Enter the iCloud ID you wrote down earlier, then click the Next button on the top right of the screen.

Continue to follow the onscreen instructions.