Hello Ian,
The Statistic Overview window shows all defined bands. The only way to delete them from this view is deleting them from Swisslog (Edit / Add / Edit bands). Deleting bands (or modes) may cause future issues if you need this band/mode added again. All modes/bands have an internal ID which is linked to band/mode reports. If you delete any of the default bands/modes and you add any of them again in a future, they will have a different ID and will cause some reports or statistics not working as they were designed. You can do it, of course, but I don't recommend it at all. Only in case you are absolutely sure you won't ever work this band or mode then you could do it but...
Instead, I highly suggest you to use Statistic Quick Views where you can select the modes/bands you like to see and you can have as many views as you like. Personally I have 6 Statistic Quick Views for 6 different statistics: DXCC, WAS, GAPA Grid, WPX, WAZ and US_Counties. These windows are very small and easy to locate in your screen. Check this out:
http://www.swisslogforwindows.com/screenshots.html
Sample desktop 3 contains 4 Statistic Quick Views and will give you some desktop ideas.
Best 73