How can parents get their violent adult son evicted from their home if there is no official police record of his violent behavior?

There is no need to have a record of violent behavior or any behavior for that matter. If there is no rental or lease agreement or the person is not on the title of the home, they have to leave at the owner's request. If the adult will not leave voluntarily, the local authorities will assist the involved parties in having the person removed. The person must be allowed to retrieve any personal items they own, or make arrangements to do so on a specified date following the eviction. If there are continuing problems after the eviction the homeowners have several legal options that can be used to resolve the issue.