It’s…gonna take months. Generally, Chatot continue to repeat things that get a response. So panicking, distracting, or reacting in any way actually gives the bird encouragement to repeat it more often and more loudly. If you steadfastly ignore the terms, the Pokémon will eventually stop using them.
Would there be any point in trying to teach the Chatot a bunch of other words, too, in hopes that it either dilutes the swearing or the Chatot decides that the new words get better responses and are more worth remembering?