ESP8266 Community Forum

I'm really searching for this but i can't figure it out to understand how this works.

I have a NodeMCU, flashed it, and then use the Arduino software to communicate with it, works like a charm.

However, when you upload a Sketch hoe would you clear the Sketch so that it reverts back to nothing on it?
Is this just a simple press of a button on the NodeMCU?

Reason i'm asking is cause i can't figure out how it would handle multiple Sketches and so on.

Really a newb i admit that

I have not used a NodeMCU, but other ESP boards generally come with AT firmware already flashed. When you flash it with a new sketch, you replace the existing firmware with your sketch. The original firmware i sno longer there, so there is no reset to get it back again. You need to get the original firmware and flash that onto the device.
As for multiple sketches, as far as I know there is no way to have multiple sketches on an ESP board at one time.