[daimon]

actually it shouldn't be that hard

If the skin you're using doesn't have the following PanelFile ID's at all then you can just add the following in the skin's SkinDefinition.xml (they need to be somewhere between <opt> </opt> tags as those start and end the skin file). If it does then just find the following tags:

For Player vitals

<PanelFile ID="ID_UISkin_AvatarPanel">
  <Element ID="AvatarPanel" X="0" Y="2" Width="280" Height="300"> 
    <Element ID="VitalsParent" X="0" Y="20" Width="300" Height="300">
      <Element ID="PlayerPVP_Info" X="-4" Y="-3" Width="34" Height="98"> 
        <Element ID="PlayerPVP_RankDisplay" X="2" Y="0" Width="32" Height="32"> </Element>
      </Element>
    </Element>
  </Element>
</PanelFile>

For Opponent vitals

<PanelFile ID="ID_UISkin_OpponentPanel">
  <Element ID="OpponentPanel" X="279" Y="2" Width="284" Height="300"> 
    <Element ID="VitalsParent" X="0" Y="20" Width="284" Height="300"> 
      <Element ID="OpponentDisplayParent" X="0" Y="0" Width="281" Height="300">
        <Element ID="Opponent_SelectionField" X="7" Y="0" Width="272" Height="120"> 
          <Element ID="OpponentPVP_RankDisplay" X="242" Y="-3" Width="32" Height="32"> </Element>
        </Element>
      </Element>
    </Element>
  </Element>
</PanelFile>

The line that you need to edit is colored green. X and Y values obviously moves the icon horizontally and vertically depending what values you use. You can even in some cases use negative values if need be but that's not always the case.

On other hand if you want to just hide the rank icon you can just set Width and Height values to "1".

Note that you need to restart your client every time you modify SkinDefinition.xml to see the effects. Relogging isn't enough.