Kamala Harris thinks so. On Tuesday she sent a letter to Twitter's CEO arguing that Trump has been violating the platform's user agreement. Harris pointed to recent tweets Trump had sent harassing the Ukraine whistleblower and the House intelligence committee chairman, Adam Schiff, as well as Trump's infamous tweet threatening civil war.
These, Harris said, constitute "blatant threats that put people at risk and our democracy in danger. No user, regardless of their job, wealth, or stature should be exempt from abiding by Twitter's user agreement, not even the President of the United States," Harris concluded. Twitter has acknowledged Harris's letter and said it will be responding.
The most compelling reason to ban Trump is that which Harris brings up in her letter to Twitter: accountability. Banning Trump sends a message that Twitter is serious about its rules and that Trump, like everyone else must be held accountable for his actions. Not banning Trump, on the other hand, suggests that you can do whatever you like if you're powerful enough.