To disable Junk Mail feature in Outlook 2010 add following registry entry on client computers via Group Policy (User Configuration > Preferences > Windows Settings > Registry)

• Action: Update
• Five: HKEY_CURRENT_USER
• Key Path: Software\Policies\Microsoft\Office\14.0\Outlook
• Value Name: DisableAntiSpam
• Value Type: REG_DWORD
• Value Data: 1

For other versions of MS Office replace 14.0 in Key Path with number corresponding to the MS Office version.

Once policy is active, Junk Mail button in MS Office UI will be greyed out.

Windows Server 2016
Windows 7 Pro
MS Office 2010