Have you tried spraying bitter apple of a piece of paper and leaving it for him to find? If it suddenly doesn't taste good to him, he may stop insisting on it. If it works, spray some tissue too so that becomes undesireable.
Also, I'd get a check up with a vet just to make sure he doesn't have some sort of deficiency that's causing the paper eating.
When he does get a hold of the paper, don't make a fuss about it. Stop trying to take it from him for a bit and just work on getting him to be neutral about you coming near him. Right now, he knows when you come over it's because you are taking his treasure away - so he's going to fight you about it. So just work on getting near him without threatening his treasure.
Meanwhile, practice "let me see it" with his toys. Ask him to "let me see it" when he has a toy and use the treat trade to get him to drop it. Pick it up and make a fuss over it. Turn it over and over, make it squeak, say "oh what a pretty toy", etc. Then watch him. If he tries to grab it back, tell him " sit". If he sits, give the toy right back. If he doesn't sit, just ignore him until he does. Do this regularly. Make it fun for him to give you the toy, while at the same time teaching him that if he sits politely, he can get it back. Make the asking for the toy very calm and matter of fact, make the giving it back a major deal with lots of good boys.
Make him sit for treats, meals, attention, etc, also. Again you want him to learn that when he sits politely, he gets what he wants.
He will pick up on that very quickly. Once he routinely sits immediately when he sees you have something he wants, start randomly saying "no more" and put the toy away out of sight and out of reach. Only do this with toys, never his meals or treats. Don't do it all the time, just once in a while so he learns that sometimes he doesn't get the item back.
So now you have been reconditioning him to see that you coming near when he has his treasured paper isn't a threat and that if he gives you his toy you will give it back and that if he wants something he has to sit for it.
At this point, you can try to treat trade for the paper again, using the "let me see it" command. If he gives it up, immediately put it out of reach and out of sight saying "no more" and give him another treat(s) for being a good boy.
This should help to lower his resource guarding because giving you his possession doesn't automatically mean he loses it. With most dogs, it becomes a game and they will start bringing you their toys because it's more fun if someone else wants it - that's why you make a big fuss over the toy itself when you get it; it makes the toy desireable. And by not doing that when you do "no more" makes that item less desireable.
One other thing is to consider where he goes when he has the treasure. If he runs into a crate or under a coffee table or into a closet, etc, then you want to take that option away from him. Getting into those places with the treasure is an attempt to limit your access to him so he can better keep you from getting it. In each of those situations, he is setting up a defensive line. It forces you to have to approach him in a specific way that gives him the edge (eg, if he's in the crate, you can only approach from one direction and at his level). By removing those options, you remove his home field advantage. This may mean keeping the crate closed during the day, or removing the coffee table from the room temporarily.