There are two ways to combat a falsehood.
The first is to combat the falsehood with truth—to provide better arguments, better data, both reasoned and impassioned appeals to rational, thinking humans. If something is true, your message will rise over the falsehood.
This is the way of liberty and of free speech.
The second way is to stifle conversation, suppress dissenting options, shout down your opposition, and delete any reference to ideas you do not like. When you do you draw more attention to the idea you are trying to stop. When you double down on it, people begin to believe that the thing you are stifling may have merit after all. The way of suppression will not bring you the effect you desire.
It is also the way of toddlers, liars, and tyrants.