To get rid of the Picasa album, go to Settings -> Accounts and sync -> your Google account -> uncheck "Sync Picasa Web albums"
The "Instant Uploads" folder is for Google+. When you first signed into Google+, you had the option to use Instant Upload, or the option to turn it off. It's also in the settings of the Google+ app (Menu -> Settings). There's also a setting for this under the above Accounts and sync. It says "Sync Google Photos."
After you deactivate the sync for Picasa and Google Photos, along with turning off instant uploads in Google+, go into the Application Manager in the settings and clear cache and data for both the Gallery and Google+. For the Google+ "Instant Uploads" folder, it's possible that you may also have to uninstall the Google+ updates, disable the app, and then re-enable it in order to completely get rid of it. I can't say 100% for sure on that one because I keep Google+ completely disabled.