Twitter allows editing the list of interests it thinks you might have but the implementation leaves a lot to be desired. It's at Settings -> Privacy and safety

Twitter allows editing the list of interests it thinks you might have but the implementation leaves a lot to be desired. It's at Settings -> Privacy and safety -> Ads preferences -> Interests. The interface is presented as a giant list of hundreds of potential interests, all ticked by default, but which must be unticked one at a time. If you start actually unticking them all or try to automate it with a script (which is the only way to stop Twitter from suggesting tweets from those interests to you, until it comes up with some new ones), the unchecking gets progressively slower until it starts throwing 500 Internal Server Errors, showing the state as changing but silently failing.