There are two ways for negative trust to be removed. First is that the default trust user or a trusted user who gave one negative feedback(negative trust) must remove their negative feedback. Another way is to gain positive trust to counter the red trust, but the negative feedback will still be there unless removed.
Apart from these (in case you receive a negative rating from a DT2 member [if you strongly believe that you don't deserve it]):1. Convince the DT1 member/members that added the user to their trust, to remove him/her (by doing this, his/her ratings won't be seen by default).
2. Depending on the amount of DT1 members that trusted the user (DT2 member), More DT1 members are needed to exclude him/her (in order for the user to be dropped from its DT2 status).
Where can I get information about Trust?
Read (all of its pages) the following threads:Minor trust score algorithm change
The latest change in the trust system has a flaw making it abusable
