Switch ON/OFF Voltage Regulator using a Microcontroller
R1 can be omitted if the GPIO of the MCU is configured as a push-pull output. The regulator allows a direct connection from MCU's GPIO pin to EN input but still a 1k resistor (R2) is sufficient.
Note that the regulator will not be enabled without MCU's enable signal. If MCU fails for some reason then the regulator will output zero.
R1's value is not that important as it prevents the regulator to run if the MCU fails or is not placed during production. It can be pulled up to +3V3 if the regulator should run without the need of an MCU (Thanks to @Transistor for pointing out).