Outlook 2013 & Outlook 2010 have reading pane which displays the email details when we browse through the messages. This reading pane can be positioned either to the right or bottom of the email list.
A Sample message displayed in Reading Pane is shown below
If you want to turn off the reading pane using the Options available as part of View menu. Navigate to View menu then to the Layout section.
In the Layout section, click the down arrow available below the Reading Pane and select Off from the list of available menus.
By this way you can hide the reading pane in Outlook 2010.
Video demo – Turn off reading pane in Outlook 2013 & Outlook 2010