Tell me if i am wrong somewhere.
Sadly, you are sort of wrong everywhere. I think you don't really know how an NPN transistor works. As mike said... resistors... where are the resistors... they are not optional.
Actually you really could be able to use servo.detach() to Detach the Servo variable from its pin, stopping the sending of signals. That would technically STOP the servo
If you want to use YOUR approach, with switching... this may work. (see drawing) Without ground, the servo won't run. (while simple, it's not really good practice though) See if you get what you want though.
If you just want control over the Servo Signal pin... you could use a CD4066 analog switch to make or break the connections to the servo signals.
