Even if you exterminated all of the Force Users in the galaxy, more of them would be born from the offspring of non sensitives. You would have to put like Ysalamir (if that's ever canon again) paste in the entire galactic food source to wipe them out or at least suppress Force Sensitivity like what the US gov apparently did to the mutants in new Logan x-men movie. That seems very unfeasible on a galactic scale it may be entirely feasible to implement such a plan on a few worlds but I doubt you could remove the presence of the Force from the Galaxy entirely.