Hi guys I’m new here and doing some modification to my truck I got bigger tires and they are rubbing a bit on the fender liners I trimmed a bit off but it’s still rubbing this plastic piece behind the fender liners my question what is this piece and is it necessary and can this piece be removed your guys input on this matter would be really appreciated as I’ve searched on what this is and can’t find anything .

 

Kinda hard to know what that is without knowing what year truck you've got.

Generally, it's not good to have to start trimming out the fender liner. Even if there are no parts behind it, there is wiring. You don't want spray washing down the backsides of your headlamp assemblies every time it rains. It's better to either reduce poke or lift the truck than trim the liners.