When you expand the layers of a multi-take vocal and want to delete layers, you have to do this one by one. Selecting multiple layers appears to work, but when you try to delete these selected layers it does not remove all selected layers, just the single one on which you right-clicked.
In my opinion this is an implementation bug, as it is not in line with common expected behavior regarding selections, which is indeed implemented in the rest of S1, but it is not seen as a bug by the development team as is was never implemented otherwise.
Bug or no bug, please fix this odd behavior as I us it quite often to clean up multi-takes and it would speed up that process significantly.