I'm renovating my Kitchen, and my stove is connected in such a way
that I'm not sure how to unplug, I added pictures that might explain it better.
I would like to either disconnect it, or make it longer.
I live in Germany, if it matters.
Assuming it's anything like the US, you'll have a dedicated breaker for the stove in your electrical panel. Shut it off first (really, it would be a good idea to do that before moving the stove for the renovation). With the power turned off, you can remove the wall plate (I don't see screws in your picture, so you may just have to pry it off) and/or remove any connectors or covers on the stove to find the connection. Just double check that the power is shutoff before you go near this with a screw driver or bare hands.