I ask this question on behlaf of my mother in law -
She is a pensioner, and wants to evict her son, his wife and 3 teenage girls from my property.
The reason is that the girls are 20,17, 12 years of age, she believes that they are into prostitution.

PLEASE SHE NEEDS HELP URGENTLY - AS TO EVICT THEM FROM HER PROPERTY

Please pay more attention to posting guidelines. There is a Read First sticky in the Children forum (where this was moved from) that directs questions of a legal nature to this forum.

It does not matter what the relationship is to the tenant to do an eviction. You need to find out what the process for eviction is in her area. There should be a local housing court that can tell her. She then follows that process. Generally the process is to give a notice that the tenancy will be terminated on x date. If they haven't vacated by then, then she goes to court for an eviction order. After a hearing the order will be granted. If they still don't leave, she hires a local sheriff (or equivalent) to physically remove them.

There is a side issue here. If she feels they are into prostitution, especially the 12 year old, she can report it to the police or child services and they may remove them.