Outlook – Remove Calendar Preview from Reading Pane in Outlook 2013

It looks like the most recent MS Office update (version 15.0.4551.1011) adds an option that allows for the message header in the reading pane to be collapsed. It re-sizes the header from this:

To this:

Once toggled, it should remain collapsed while switching among messages. Go to the File tab -> Office Account to check your version and update.

I'm doing this from memory, I'll double check all the steps in about 10 - 12 hours and edit my answer if required, but I think this is how to do it. Down at the bottom left hand side of Outlook it says: "mail - calendar - people - tasks - ..." click the ... and go to "folders" there you should see the folder structure that includes the duplicate calendar files. You should be able to right click and delete, or move the calendars to different locations.