Goodreader is probably the most popular way to view KrPano's off line on iPad. While it has a lot of issues, figuring out a way to exit the 360 has been a common issue. You can add links to a PDF, or external site (only works if wifi connected) or use a full screen open with then a button to close full screen.
Anyway, all of these solutions can easily be put in the past, I've found a very simple way to exit - just use the log!
Open the log by swiping up from the bottom right corner, tap in the log area and you've got your goodreader exit.