It's built into the minimap. Your only option, aside from physically replacing the arrow texture (which I don't think even works), is to un-track the quest it's pointing to.
Try this..
Lua Code:
SetSuperTrackedQuestID(0)
hooksecurefunc('SetSuperTrackedQuestID', function(questID) if questID ~= 0 then SetSuperTrackedQuestID(0) end end)