It's understand that the side panel take some real estate in of your screen, you can simply click >> icon to minimize it.
But, if you want to really hide it, follow below steps:
- From Microsoft Outlook, click on the down arrow to show the options for the Quick Access Toolbar
- Click on 'More Commands...'
- On the Outlook Options window, change the 'Choose commands from' option to 'All Commands'
- Scroll down to 'Salesforce Side Panel' and add it, then click OK.
This will create the round icon, and if you click it, you will see the option to easily Show/Hide the Salesforce Side Panel. When it is hidden, it will take less resources, but the agent still active for sync process.
This blog is written with Salesforce for Outlook version 2.9.3 with Microsoft Outlook 2013 on Windows 7 machine.