Is there an easy removal trick for the Mopar large headed plastic “rivets” on under body splash shields and inner wheel well liners?

In the past I have always just snipped them off with electrical side cutter pliers, and then bought new ones,
but I thought:
“maybe there is a slick trick to remove them and then re-use them.”

I just tried wrapping thin but strong fishing line around the head and pulling down, but no luck.

I just take a real thin flat head screw driver and wiggle the top pin up enough to pull all the way up with needle nose pliers and then I wiggle the base out with larger flat head and pliers for the one type and the other type just a big flathead and I wiggle it up all around the base and needle nose pliers after I work it out some.

if its the actual rivet style (mandrel) you can push the center out with a pin punch and they will fall out

You have to be able to get to the underside to push it out and you can't always do that. I just replaced headlight assemblies on a 2010 Charger and there are a bunch of both types and the underside are not accessible.

Side cutters are the easiest way I've found but I don't use them to cut the rivet. The side cutters will get under the head fairly easily. Then you just twist the side cutters side to side and the rivets usually pop out. I'm talking about the solid type...not the ones with the extra center piece that pops up.

Snip and replace

None of the tools cost much to buy.

I use these. More than one because sometimes you can't get leverage for one so I use the other.

The black handled pliers are for the rivets with the notches under the head to allow you to pull the nail out of the rivet.

For years I used a dull set of side cutters like burdar suggested.

i am a certified autobody tech. i install thousands of fasteners monthly.

plastic rivets are NOT REUSABLE. you have to replace with another rivet or a comparable push in fastener. they use a special rivet gun to install. a lot of times the inner plastic pin breaks when installing. they are somewhat a pain in the rear to install sometimes. so most times i just cut and replace with a push in fastener when i can.

the plastic push in fasteners, like the "christmass tree" earlier pic of one, are rather difficult to remove and reinstall without damaging the part they are attached to. they twist the fender tabs holding them in when you try to save them. on them pushed into a solid part i use a bent end long nose pliers and pull them out.
on fenders i just cut with a side cutters and replace.

the push pin fasteners are easy to remove and replace. just pull the inner pin out with a side cutters or comparable tool and the outer pin usually falls out. sometimes a bent end pick works great to remove the inner pin.

in most body shops have a bin with extra fasteners. i just go into the bin and find another comparable sized one for a replacement part.

I guess I used rivet as a generic term when I should have differentiated rivets from retainers. Sorry about that.

You are correct, the Rivets that require a rivet gun to install are not reusable. The Christmas tree ones are often damaged when you pull them but GM likes to use those on wire looms and replacements are hard to source locally.
The other retainers are reusable.

On those fender retainers that bend the fender flange you may try the green handles pliers above. They don't always fit but they press and pull at the same location so they don't distort the fender.

i have, and use, a multitude of different tools to remove those retainers. some home made, and others like shown above.
i also have a couple of boxes of different types of retainers on hand to replace as needed.
some of those can be a real pain to remove, even with the use of tools.

I bought the Performance Tool W86556 clip removal pliers $22 at Advance Auto which is similar to the green handled plier in the picture above and it successfully removed 4 of five plastic “Christmas Tree” fasteners, and broke the head off the other.