Here is an important read that, while it does say that in Arizona, a land owner can cross another land without permission and if they get away with it for 10 years, does have a right to continue, but must meet other criteria such as no other way of access. Also no where does the law say anyone using the road under prescriptive easement, has a right to say if the owner of the road can gate it, but would address locking the gate and denying access. The owner of that land, can divide it into several pastures and put up 15 gates if they want and all using that road, have to comply with shutting the gates after use.
Whether the guy that removed the cattle guard had a legal right, is between the land owner and him. It isn't any other land owners, using the road under prescriptive easements, concern. Also the land owner isn't responsible for maintenance on the road. If it washes out, then that would be tough luck if the owner didn't want to repair it. No one using it under the PE law, has any rights other than passage, using it to get to their property that would be land locked without this access.
I can't imagine anyone buying a place with a road to it, that offers no deeded rights to the buyer.
My suggestion to resolve this problem, is to contact the land owner and all that use it, and talk about getting deeded rights. This would cost everyone but the land owner money, but would make the users property more valuable. I doubt a lawsuit would do any thing but cost you money. You would have to sue the landowner, not the guy that took out the guard. What losses would you sue for? You can still use the road, but it is just inconvenient. I doubt any judge in ranching country, is going to grant a money reward because you have to get out and open a gate. A judge would rule . yes you have a right to use the road, but that is it. Just be thankful you don't have to open 6 gates and they are all barbed wire.
If you owned the property where the guard was removed, you have a case, but without a deeded road agreement, you are at the mercy of the land owner whose land was crossed without legal agreement for the past 30 years.
In short, prescriptive easement under Arizona law, does not give anyone rights or even a voice to demand ungated access. Whether the guy that removed the guard, had any right to do it, is between the land owner and him. Sorry, but free use users cannot demand anything, but use of the road for passage to their place. They cannot demand maintanence or dictate how many gates have to be opened and closed.
https://legalclarity.org/arizona-easement-law-types-creation-and-enforcement/