My email appears in iCloud after I reset my iPhone?

I want to sell my iPhone 4S, so I restored it and reset all setting on it. I then went to check all the settings to verify that all my information was gone, but when I get to the iCloud section my email is still there. I reset it multiple times and restored all of the setting as well. I don't feel safe selling my device when I know some one will have my email address and do something unwanted with it.
Does anyone have any idea on how to fix this? Apparently resetting the whole device won't work so I don't really know what else to do.
iPhone 4S, iOS 6.1, I tried to update to 6.1.1 but it says it's up to date, any help on that would be great as well.

I think that you need to visit at the iPhone repairing shop. They have code of the format and restored the iPhone. Otherwise you need to visit at the Google searching site. You have to found the solution of the this kind of the problem. Then you have to follow the step of restored the iPhone which show by the Google searching site.