https://slate.com/news-and-politics/2001/02/can-congress-impeach-bill-clinton-again.html
Can a former president be impeached?
Apparently, yes. Obviously a former president would not be subject to removal from office, but scholars say that Article I, Section 3 of the Constitution, which says that impeachment may result in “disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States,” could apply.
In practical terms, an impeachment would mean Clinton could not serve in any other federal elective or appointive office.
Why didn’t that apply to Alcee Hastings?
Impeached federal judge now in Congress!