You can't do anything. Trust isn't moderated. The only way to get the trust feedback removed is if you talk to the user who gave it to you (The Pharmacist) and he agrees to remove it (I doubt he will).
And you don't need to have done any trade with the user. You are an one-liner shitposter and that's what the trust says. So it's probably valid.
I did have post one liners but that's all I has to say, though they're short they already have the thought in it, And Not all my post are one liners I'll even put a link of my sources when I have to. Are there rules saying you are shitposting when your post is below 2 paragraphs or below a certain number of characters? Should I delete my one liner posts?