The MySync calendar is your default sync calendar. It is built for you automatically if you have not chosen another calendar in your MyCalendars panel as your sync calendar. Just like any other calendar that you own, you can delete it or unsubscribe from it.

You might be thinking "Okay, exactly what purpose does it serve?"

You may have many calendars in CALibrate and decide to sync with Outlook. When you add an event to Outlook and synchronize with CALibrate, we don't know on which of your many CALibrate calendars to put the event(s) unless you tell us. And if you don't tell us, we build one for you. Thus, MySync!

You can quickly visualize what is your default sync calendar because it will have a small green dot next to the sync or don't sync icon as shown below: