If that is a concern, you should try to provide your proof to the person who gave you the negative trust, which he may or may not believe. Be as clear and explicit as possible depicting the events and providing the proof you say you have. Nobody else will be able to remove that negative trust, although you could also open a thread in Reputation to defend your case publicly. Bear in mind that this sometimes turns out wrong, as the debate sometimes leads to more people distrusting the defendant due to the proof provided by one party or another.

Regarding your first negative Trust from 2017, that is going to prove to be even more difficult to tacle, since @Vod has declared having left the forum (Edit: see https://bitcointalk.org/index.php?topic=5329366.msg56741167#msg56741167)