If you use Office 365, then this is a server-side microsoft issue. The following service alert was posted on the office 365 service status:
Current Status: Engineers have received reports of an extra calendar folder appearing in some user mailboxes. Engineers have identified the cause of the issue and are developing a fix to resolve the issue.
User Experience: Affected users have an additional calendar folder in their mailbox that cannot be deleted titled "TimeProfile". The extra calendar folder does not affect the user's primary calendar and can be ignored until the fix is implemented to remove it.
Customer Impact: Customer impact appears to be limited at this time. This issue affects users connecting through Outlook for Mac and Apple Calendar.
Incident Start Time: Thursday, January 15, 2015, at 12:00 AM UTC
Preliminary Root Cause: As part of our ongoing efforts to implement new feature improvements, an update was deployed to the calendar service; however, the update caused a hidden system folder to appear in the mailbox for Exchange Web Services (EWS) clients.
Next Update by: Monday, January 26, 2015, at 9:00 PM UTC