a hyper-concrete alibi usually works (such as reliable documentation of being on a different continent), but everything else is just "absence of evidence" (not a clearing).
unless "cleared" actually just means "insufficient evidence".
Did what? The allegations weren't even put to the "accused" let alone a court of law.
Let me be clear, I don't know whether he was guilty or not, the biggest reason being that the accusations are public.
But that's the rub, just an allegation can be enough to trigger all sorts of repercussions regardless of the guilt of the accused.
Accusations should be taken seriously unless prima facie absurd (the raped by someone who wasn't in the country for 20 years level of absurd). And in most cases should initially lead to suspension pending investigation for offences that would lead to a custodial sentence.
Firing and other forms of response where there is no way back is prejudicial and lacking natural justice.