iOS Wifi restrictions / Airwatch removal

Hi

I've not been able to find anything in Airwatch to do the following but would appreciate if anyone knows different:

Is it possible to restrict iOS devices from connecting to Open wifi networks or Wifi with a Captive portal ? Our devices are all supervised by Configurator 2 but we cannot use the Whitelist Wifi function as we have too many networks allowed. 

Also is it the case that devices have to be in DEP in order to prevent the removal of Airwatch MDM ?  I believe so.  I've removed the Unenrol option in Hub but they can remove the profile.

Thanks
Adam.