Can I safely delete duplicate calendars?
A multiplicity of calendars has been created by an unknown force
resulting in event notifications cascading down the R side of my
screen. Each calendar seems to have the same info and only one
is activated in Prefs. Deleting one (Control-click on it) takes a full
minute - there isn't any other obvious way to delete. What's the
root cause of their creation? Thank, Tom
Pic from Calendar Prefs
MacBook Pro (13-inch Mid 2012), OS X El Capitan (10.11.5)