how can i logout from my gmail account from my mobile phone? my mobile phone is sony erricson XPERIA U.
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You can't without deleting your Google Account from your phone as far as I'm aware. You can do this in your phone settings. Why would you want to though?
If you are concerned about people seeing or using your email, set a PIN or pattern lock on your phone.
Alternatively, remove your Google Account completely and use Google's web based versions of Gmail, etc. All of those you can log into and out of at will - obviously a lot less convenient though.