To delete a column from the Sequence Editor simply move your cursor to it and hit CTRL-Delete. This may also be accomplished by Right-Clicking and selecting "Delete Track" from the pop-up.

To prevent mistakes, Buzz will then pop-up a dialog to confirm the deletion of this column.

Note: Deleting columns does not delete the machine or patterns used, from the song itself. This must be done in the Machine View and Pattern Editor.