Hello , I have done an Iot apps that can turn on/off LED from esp32.. I wonder If i can replace the LED to arduino uno, so that I can turn on/off the arduino, can I just connect the gpio output pin from esp32 to power the arduino uno from the 3.3v pin at the arduino uno.. ??? Is that possible ??? The project Im making for the arduino is vacuum cleaner, Im adding the esp32 just for iot to turn on/off the arduino.. Power supply(Powerbank) --> ESP32 --> Arduino Uno.
Hello , I have done an Iot apps that can turn on/off LED from esp32.. I wonder If i can replace the LED to arduino uno, so that I can turn on/off the arduino, can I just connect the gpio output pin from esp32 to power the arduino uno from the 3.3v pin at the arduino uno.. 
Is that possible The project Im making for the arduino is vacuum cleaner, Im adding the esp32 just for iot to turn on/off the arduino.. Power supply(Powerbank) --> ESP32 --> Arduino Uno.
There are number of things wrong with your plan
1 - you cannot power a Uno by supplying 3.3 V to its 3.3 V pin
2 - even if you could then the Uno would take more current than a GPIO pin on the ES32 can supply
3 - The ESP32 should not be considered as a power supply beyond the small current requirements of say an LED
If you really want the ESP32 to turn the Uno on and off then consider using a relay or a MOSFET or better still have the Uno on at all times but signal that its code should run by connecting a GPIO pin of the ESP32 to an input pin of the Uno and detecting its state
If I add a relay, which power supply pins at the uno I should connect ?
@ hafzam
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hafzam:
If I add a relay, which power supply pins at the uno I should connect ?
What voltage does the powerbank provide ?
If it is 5V then have the relay provide power to a 5V pin and GND
If it is 12V then have the relay provide power to the VIN pin and GND
Why even use an Uno in this case? An ESP32 developer board should have a good number of pins available.
OK, this does outright win the "bizarre question of the week" award. 
Pretty much everything is wrong! Using two processors, switching power to the processor, using the more power hungry processor to switch the less power hungry processor, using a relay, using a "Power Bank".
It clearly takes the "XY Problem" award. 
If you wish to begin to make sense, start by explaining what an Arduino could possibly have to do with a vacuum cleaner. That may be worthy of some discussion. Are you perhaps attempting to re-invent the Roomba? That would clearly be a total waste of time. 