Hi again, floyd

BUT the first 7 tracks play by different rules (you cannot get them "empty")
The original BIAB 7 tracks are defined in the creation of the original style. So when a style is loaded, whatever tracks were gathered together to make that style will be the ones that cannot be erased. If you want to fully clear a track that's defined in the original style, it's necessary to edit the style (File >> Stylemaker >> Edit current style), clear the track, and save the style as a new one (unless you would prefer to overwrite the existing style). As with all computer files, when an existing style is overwritten, the original style will be lost and it will be replaced by the new version.
If you want to stop a style-defined track from functioning, it's possible to disable it by unchecking "Track Settings >> Enabled". This is a toggle and will disable the track. It's also possible to uncheck which tracks are visible using the "eye" on the lower right of the mixer. This is a useful way of reducing what's visible. The "Show Active, Hide Inactive" option under the 'eye' is also useful for condensing the on-screen display.
I hope this offers some insight.
--Noel