My application starts up another external application.
I want to remove the title bar of this external application once it has started.
Is this feasible, and
In general, you can't do that unless there is direct support for in by the application you are starting (for example, if it takes a command line switch for removal of the title bar).
You can only control the things that are already present on the ProcessStartInfo class (i.e. open a new window, start minimized/maximized etc...).