It can be removed by dealing lethal damage to it or by reducing its toughness to 0. If a player has two copies of Rules Lawyer, however, then each one will protect the other, and some other kind of effect will be needed to remove it.
Strange. (704.5p) Because Rules Lawyer applies only to you and other permanents you control, tokens that leave the battlefield will continue to cease to exist. This is also true for copies of cards that might exist off the battlefield.
Any ability that says a player wins or loses the game still works. Rules Lawyer’s ability doesn’t apply to itself. It can die for any number of reasons. If you’re at 0 or less life and you lose control of Rules Lawyer, you’ll immediately lose the game.
Permanents you control attached or combined illegally remain on the battlefield. For complete rules and regulations, see rule 704.) You can control as many legendary permanents (including planeswalkers) with the same name as you want. It’s like your own personal Mirror Gallery! (704.5j)
In Commander, you’re immune to the “commander damage rule” that says you lose if a single commander deals 21 or more combat damage to you. (704.5u) 1/19/2018. Because Rules Lawyer applies only to you and other permanents you control, tokens that leave the battlefield will continue to cease to exist.
Rules Lawyer’s ability doesn’t apply to itself. It can die for any number of reasons. If you’re at 0 or less life and you lose control of Rules Lawyer, you’ll immediately lose the game. A creature with toughness 0 or less can still attack and block.
State-based actions don't apply to you or other permanents you control. (You don't lose the game due to having 0 or less life or drawing from an empty library. Your creatures aren't destroyed due to damage or deathtouch and aren't put into a graveyard due to having 0 or less toughness. Your planeswalkers aren't put into a graveyard ...
If you somehow control a creature that’s attached to another permanent, that creature can stay attached. It can attack and block, even if another creature is carrying it. Similarly, if you control a permanent that isn’t an Aura, an Equipment, or a Fortification, it can stay attached to whatever you manage to get it attached to. Strange. (704.5p)
They may not do much because there probably won’t be an “enchanted [whatever],” but they’ll stay on the battlefield! (704.5m) Similarly, thanks to an un-documented silver-bordered state-based action no longer applying, your creatures with augment can now survive even if not attached to a host . If this happens, its power and toughness are 0/0. (704.5m)
Your planeswalkers aren't put into a graveyard if they have 0 loyalty. You don't put a legendary permanent into a graveyard if you control two with the same name. Counters aren't removed from your permanents due to game rules. Permanents you control attached or combined illegally remain on the battlefield.
Simply put, if you and I agree to play american football, a touchdown is worth 7 points (or 6 plus the extra point kick that most sandlot football does not do). If I score a touchdown and you all of a sudden decide that it's only 3 or 4 points, then I am going to cry foul. I have played in RPGs where as the new guy, I try to do something to be told "that's not possible", yet an established player character does something so similar a few rounds later that I could not tell a difference. "Hey, you said I couldn't do a Spinning Death Attack, but George can do a Twirling Kill Attack!" A player in this situation will do one of two things; either they will leave your group/the rpg community because "those guys screwed me over"; or they will learn that rulebook and everything in it so when they want to do a Twirling Kill Attack/Spinning Death Attack, and the DM says "nope", they can say "Actually, yep. I use [feat], [skill], and [action]".
It simply means that the rules exist only as a GUIDELINE to play in your world, and you set the exact parameters. With this in hand, rules lawyering stops cold.
The easiest solution is to re-skin or tweak monster stats. Give it a name that's not in any manual, borrow another monster's stats, and change up the weapon and description of the attacks. Now it's a monster they don't know anything about!
One of the holes in all the answers thus far is that they take an adversarial approach to rules lawyers. That will only antagonize him more, which will only exacerbate the problem and build up to a "dude, leave our group you jerk-face" moment. Defuse the hostility and you can go back to being friends again!
The other kind will only cite rule knowledge when it is to their advantage. There are many ways to deal with this kind of player but in my experience it is best to discuss the matter with them outside of the game, away from other players. Find out why they are so concerned with getting their way. If they are being disruptive to the group or flow of the game with their behavior, be sure to express that. In my experience this usually results in asking the difficult player to leave the game. Don't give them the chance to rant in front of the group if you can.
Basically, if the players taking fun away from the game, talk to the player out of game, and away from the other players. Just be polite and open. If the player is reasonable they will understand.
Oh yeah, Rules are used and not used at the DM's discrection.