I not sure that is the only thing we need to do. For instance, Trump regularly threatens violence on twitter and doesn't get banned. So perhaps they have a conservative bias. Using your sort of puerile logic, anyway.
Do you mean President Trump has threatened a specific individual with violence? Can you give me an example? What part of my reply do you consider childish?
I appreciate you taking the time to research and share that link, but the third paragraph in that article states, "But Twitter says the president’s tweets do not violate any of its rules...". And once more in the 8th, "But in this instance, Twitter has opted to leave Trump’s tweets alone, finding that they are allowed under its rules." This does not seem to be an example of President Trump violating Twitter policy.
Twitter has a history of great flexibility for famous accounts. E.g., in 2017, Twitter introduced the "newsworthiness" exception for tweets pretty much guaranteeing that anything he says is allowed under the rules. Many people feel that Trump gets much greater latitude compared with what some 20-follower anime-avatar account would get.
I certainly believe that's the case. In some ways, Trump saved Twitter. Their numbers improved greatly when he came along. Even ignoring the fact that banning Trump could be incredibly bad for Twitter in PR and regulatory aspects, kicking him off would cause a significant hit to key metrics.