how to verify if iphone has removed my info before trading in

Perform all of the steps in What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

If you still aren't sure, turn on the iPhone and it should take you into the setup: Set up your iPhone, iPad, or iPod touch - Apple Support

Headache101 Said:

"How do i verify that my info has been removed from old iphone before trading in"

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Important:

Verify it is Disassociated:

Once all is signed out, be certain it is disassociated from your Apple ID. Use the following long to view your devices.

Go Here: http://appleid.apple.com/account/manage