How do I get someone to move their mobile home off my land? There is no rental agreement. Can I move the trailer myself?

There is some sort of agreement, it would be the one, even if verbal, that allowed them to put the home there to start with.

So how did it get there? What was the agreement to put it there.

Was it there when you bought the land?

Without a written agreement, you are free to put in place an agreement, that is normal and usual. Charge them rent and provide those services required.

If they do not pay, you can go to court to order them to move the home.