I managed to disable Instant Upload, but it already pumped hundreds of photos from my iPad to my Google+ account. I'd like to delete them en masse. I can't find a simple way.
I can drag a selection, but it's very slow to scroll down in Chrome (the pictures are big in the Instant Upload view, G+ slowly scrolls the selection down). I can't find a way in the iPad/iPodTouch version of G+ either... This thread addresses the issue, but I can't make sense of it (perhaps on the Android version it's obvious?).
I had the same problem as the OP: Google+ had uploaded 800MB of photos on my mobile without prompting me. Here is the solution I've found to delete whole album, which was not available in Google+ interface. Open https://picasaweb.google.com/home, there you'll see the instant upload photo album and the option to delete the whole album.