Originally Posted by JakeChance
The culprit here is Google+. First go to it and disable instant upload. Then go to it's app information either through Settings -> Apps -> Google+ or by dragging it from the app drawer to the top of the screen. Force stop it and then clear it's data. Do the same (force stop + clear data) to Gallery. Your picasa pics should be gone now.
Thanks JakeChance! That worked for me.