How can I disable NLA in WMS 3.2.1 or ThinOS 9.1.2101

I want to go directly to the Windows RDP logon screen on a server and bypass the Dell RDP logon screen. When I tried to go under Global Connection Settings - RDP - Enable NLA it is Greyed out. Under WMS 3.x ThinOS 8.5+ there was a setting to disable or Enable NLA but under ThinOS 9.x it doesn't exist. Any ideas or am I looking in the wrong direction?

Thank you.