American Atheists fired David Silverman, the organization's long-serving President, following a brief investigation into multiple complaints they received. You can find their statement here. The statement links to a BuzzFeed post that goes into way more detail about the allegations against Silverman. I'm choosing not to link to that post here because I do not wish to promote the sort of clickbait-oriented outrage media in which BuzzFeed traffics (unless it has to do with manspreading).
The allegations made against Silverman are concerning. My assumption is that American Atheists conducted their own investigation before making the decision to fire him. If they found that the allegations had merit, it sounds like they had more than enough reason to fire him. Some will consider this assumption (i.e., that they investigated the matter and found the allegations had merit) naive on my part and argue that they may have dismissed Silverman merely to avoid the bad press of keeping him on. They may have accepted the allegations at face value without any meaningful investigation. All I can say is that I sincerely hope this is not the case.
American Atheists will likely survive Silverman's departure; however, I have to admit that he's become synonymous with the organization in my mind. As a result, I have a hard time imagining what they'll be like without him. I guess we will find out soon enough.