Have someone who was verbally informed that they are no longer allowed on the property and the person returned to the property stating that they did not have to leave and that if I wanted them to leave that I would have to have them evicted.

We need more details. 'On the property' - land? House? Barn or other outbuilding? Living in a camper? Do you live there? Do you share living space with each other? Was there a contract, ever?

In general, once someone has established some sort of tenancy, they do have to be evicted. Often proving they live there only takes 30 days of proving they have a number of possessions there and get mail delivered there.

So evict them! As Joy said, once they have established residency, they have to be treated like a tenant. Find out the process for evictions in your county and follow it to the letter.