I have never seen anyone who can remove redtrust from an account. If you want to reduce it, you should probably get users to trust you. However, your trust history can never be changed. So sad.
As a matter of fact, negative trust can be deleted, but it only doable by the each individual who gave the negative in the first place. For example, a person from my local board was, at some point, accused of spreading malware through after creating a fake Ann thread. After thorough investigation, there was sufficient proof that his account had been taken over to perform that act, and the negative trust ratings were reversed to neutral, with an explanation as to what caused the negative to be reversed.
It is perhaps not a frequent outcome, but if one can vouch for his case by bringing solid evidence to the table ,that refutes the negative rating accusations, then they have a chance of them being review and removed. This is not likely at all to happen in this case though, since the account was within a set that are connected and participated in the same bounty, which is tagged if caught