How to Disable Folder Synchronization in Outlook 2007
Emails and calendar folder items can be synchronized with folders on your computer for the Microsoft Outlook 2007 application by enabling the Cached Exchange Mode. This feature makes a copy of your files and stores them as .ost files on your computer. If you no longer want the folder synchronization to occur, manually disable the Cached Exchange Mode feature. Using the Account Settings option in Outlook 2007, you can select the Exchange server you are connected to and then make sure the synchronization stops.
Open the Microsoft Outlook 2007 program on your computer.
Click the "Tools" option from the top toolbar menu and then click the "Account Settings" option.
Select the Exchange server account that your Outlook 2007 application is connected with and then click the "Change" button.
Click the box next to the "Cached Exchange Mode" field so it's deselected below the "Microsoft Exchange Server" section.
Click the "Next" button and then click the "OK" button. Click the "Finish" button to close the dialog box.