Don't know as I've never tried to replace my T-120's front sight. I can tell you that the front sight is not compatible with Cz75B replacement sights, unlike some of the other Canik made Cz75B Clones.
Just looking at it tells me that the Barrel Bushing has to come out and the Front Sight then drops out the bottom, rather than pulls out from the Top.
Don't know exactly how the the Barrel Bushing should be removed.
You might consult a local and competent Gunsmith, who is familiar with the design.

TriStar/Canik T-120