TO get rid of HUD that shows shields, press F9, you will lose shields and mine rings, distance to target, target speed, etc...
You also lose this for both yourself and the enemy.. but you can just look at your enemy silhouette under your ship on the left control panel.. it too shows shield strength of enemy.
You can also edit the files in the textures folder for the shields to be transparent as well as mines.. however I don't think BMP files allow for that, maybe just a black color... however there is no way to alter the silhouette showing the enemy weapons and shields or even your own.. those are contained in the sprites.q3 file...
BUT remember, if you edit the texture files, ONLY YOU CAN SEE THE CHANGES YOU MAKE.. if your shields are black or transparent, your enemy will still be able to see shields just fine and there is no way to CRC check that.. so if you make a Mod, just remember that the other players can just restore the altered texture files back to the originals to regain the visual effects, thus making the Mod moot... Your enemy will have a clear tactical advantage over you because they can quickly see your shield strength and keep hitting the weakest easily where you will have to keep refering the the silhouette. And since the textures have absolutely no effect on playability or balance and is not considered a cheat at all... just personal preference.. texture files do not get checked for tampering.. as such.. alter them at your own risk. Not all players will want to have those files modded and can easily change them back to defaults.. just keep that in mind.