Electrical siding pass through removal
Turn off the power to this circuit (hopefully you already thought of
that.)
Take off the cover of the box on the outside.
Take another picture, but it would be quite normal to find screws holding the box to the building as well as the conduit. Loosen or remove those screws, that may give you enough motion to do what you need to do.
If you resort to lubricants/penetrants, remove the wires first. Then use the petroleum products, then clean everything up before reinstalling the wires.