Yes, someone who owns land may kick anyone off the land that they own, no matter how long that the other person has lived there: living on another person's land does not give you ownership rights, or even a "life tenancy" (the right to stay there during you life, but not sell or pass the property) over it. Ownership means the right to control who may use, possess, reside on, etc. the land. Ownership is not negated by the fact that someone else may have been allowed to use the property for some period of time.