Trying to remove air condenser, how to remove power cords from it?

I'm trying to uninstall air conditioning system on my own. In my room the conditioning unit connect via pipe to outside condenser unit.

The air pipe is straightforward but the power cords that this condenser received power from in my room, has this weird 3-cords socket I can't figure out how to remove it. I don't know its name so I also cannot search for it.

This should be a kind of removable but it doesn't have any kind of lever to unlock these 3 cords. I tried poking in every holes while pulling the cords out but nothing works. I took some photograph of it. Do you know how to remove cables from this socket?