That's the cone
clutch F-N-R lever hub at the
helm, right? The lever was held on the hub with the nut you are holding in the second picture? The question is how the hub is held on the shaft? If yes to all the above, I'd look for a set screw in the hole at the top of the hub.
The alternative is that the shaft and the hub have a matching flat or a key/keyway. In that case, you'd be able to pry the hub off the shaft.
Overall, it sounds like your
cables are in need of disassembly,
cleaning, lubricating, and possibly replacement.
Good luck with it.
If I missed the point entirely, how about
posting some more information about the situation? Here's a link to the manual, but it appears you are dealing with the
helm end, not the engine/tranny end.
https://www.jeanneau-owners.com/Manu...s%20Manual.pdf