Re: how can i delete photos that were auto backed up off of my Galaxy SGH-T599N?
Welcome to Android Central! Go to your Google+ Photos page on your computer browser, select Albums view, and look for your backup folder. Delete it on the web.
On the phone, go to Settings>Accounts-Google>[your Google account], and uncheck Picasa and/or Gallery. Now go to the App Manager, select Gallery, and Clear Cache/Clear Data, then Force Stop. Open Gallery again, wait a few seconds for the database to rebuild, and you should see that those backup photos are gone.