Disable Account Changes in Outlook Express

Open registry and create below key

System Key: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Outlook Express]
Value Name: No Modify Accts
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = default, 1 = enable restriction)

If you are an admin managing network computers, before trying to make any changes to account setting use regedit option "connect to network registry" in admin privileged login and change values to enable before going to edit in user login

that should do the trick !!!