I am having this issue as well.
I have Jellybean (4.1.2).
My entire Google account is sync disabled.
I have gone into the Settings>apps>Gallery and force-stopped and cleared the cache and the data.
I have gone into the Settings>Media Storage and force-stopped and cleared the cache and the data.
I have also gone into the explorer and deleted every Picasa folder I could find.
And I've gone in to Settings>Apps>Picasa Uploader and disabled it.
As soon as I open the Gallery only the camera photos appear...for about 3 seconds, then everything else shows right back up again!
.
Someone had suggested signing into picasa.com and deleting them from there, but that redirects to picasa.google.com and wants me to download a program.
Please help?