Impeachment was declared on a single article-sedition. The resolution states that Trump’s actions comply with the constitutional wording “serious crimes and misdemeanors” for which the president can be impeached.
To remove Trump from power ahead of schedule, he must be convicted following the results of the process in the Senate. Still, Republicans have not yet agreed to recall the Senate from recess before the inauguration of Joe Biden on January 20. Would it be possible to make Trump the impeachment retroactively after his resignation, it is unclear: this practice has never been seen in congress’s history.