I have an application that runs using as AsInvoker manifest, this uses ProcessStartInfo to run another application that is using a HighestAvailable manifest (in my case this runs as Admin and I get the UAC prompt) the first app then quits.
The second app then uses ProcessStartInfo to run the first app again, this time it runs as admin (no UAC prompt) I guess this is correct because it is AsInvoker and it is being invoke from an application that is running as admin, but I actually want it to run without Admin rights - or more correctly run it with the lowest possible execution level
I know you can use ProcessStartInfo.Verb = "runas" to elevate but can you descend?
No, you cannot "go back down" (There are several answers on this site and external tutorials that claim otherwise, but they all have problems in certain scenarios, this answer from a MS employee confirms that this is the case)
Your only real option is to use a AsInvoker bootstrapper/parent process that can launch unelevated processes. (And even this will fail if the bootstrapper is started elevated, but in those cases the user manually chose to run as admin)