Ideally, if the program has available a command line switch to close it, then you can just "launch" the program EXE with the termination switch (e.g. "Program.exe -exit"). But most programs do not have such a command.
Alternatively, since "Launch application" is a command line process, you can enter a command to kill the system process. BUT this is usually not a good idea because it is not a clean shutdown. It is basically like the program has crashed, with all the consequences thereof. So for example, you could launch "TASKKILL /f /im thunderbird.exe /t" - which will forcefully close Thunderbird ...but you probably will not like the result.
Better than killing the process would be to find a third-party tool which you could launch to cleanly close the program.