To prevent a new .ost file from being created
In Group Policy, load the Outlook 2013 template.
To prevent a new .ost file from being created, open the Group Policy Management Console (GPMC) and, in the tree view, expand Domains and then expand Group Policy Objects.
From the short-cut menu (right-click) of the policy object that you want, choose Edit. The Group Policy Management Editor window opens.
In the tree view, expand User Configuration, expand Administrative Templates, expand Microsoft Outlook 2013, expand Account Settings, and then choose Exchange.
Open (double-click) Do not create new OST file on upgrade.
Choose Enabled to enable the policy setting and then choose OK.
well works in 2013 so should work ok for you
or,
he following is what we use in our GPO to prevent OST creation. These GPO settings are under 'User Configuration \ Administrative Templates'
Microsoft Outlook 2010/Account Settings/Exchangehide
Policy Setting Comment
Do not allow an OST file to be created Enabled
Synchronizing data in shared folders Disabled
Microsoft Outlook 2010/Account Settings/Exchange/Cached Exchange Modehide
Policy Setting Comment
Download Public Folder Favorites Disabled
Download shared non-mail folders Disabled
Use Cached Exchange Mode for new and existing Outlook profiles Disabled
