Deleting and minimizing calendars

In the left column of Calendars both AOL and Google are listed in addition to iCloud. I do not use these and there are no entries there. Is there a way to delete AOL and Google from the column? I have looked in the menus and right clicked and do not see a delete option.

Also, is there a way to "hide" the iCloud sub-calendars? When I pass my cursor over iCloud the Hide option does not appear.

Thanks.