Thanks @bmillham and also @Soli
I turn-off the CEC via TV and installed the IR extender and seems to be current available remote options via OSMC Settings --> Remotes not compatible with my Samsung TV remote as when selected no keys working in the remote.
I dug-up old Samsung TV remote which showing in the picture of OSMC and that one works with OSMC but not with the TV so I am back to my issue of having 2 remotes.
Any way I can add my TV remote to OSMC remote list? Or how I can overcome this new problem?