Unwanted SPAM calendar events (Cannot delete)

[WallyZ21]

Mysetup

Xperia Z1
Kitkat 4.4 build 757

After a failed 681 to 757 update I was forced to reset before updating. (So phone is fresh setup from only a few days ago).

With exception of the following (facebook, Kobo) nothing is set up.

I hopped into the build in calendar app and found an advertisement (SPAM) event for a local pub.

The event cannot be deleted or declined.

My questions are:

1) Where did this event come from?
2) How can I secure the calendar app or phone to stop this from happening?

 

[WallyZ21]

Disregard.

It was a setting in the Calendar App:

Calendars
Xperia with Facebook (Checked)

I unchecked this and the facebook event disappeared.