Shorting NPN transistor base to ground

The base of a CE (common emitter) NPN transistor circuit can be safely shorted to ground and the effect will be to turn the current in the collector OFF.

Some designers prefer to use a resistor, often because the base is also driven to a + voltage level and they want to limit the base current. But in your circuits above, you can leave the resistor in the path to ground out if desired.