The landlord will not be the one to force anyone out.
That job would ultimately belong to the local law enforcement once the landlord obtains the appropriate order from the court.
The landlord does have control over who resides at the property. Usually a new occupant is required to at least clear a background check with the landlord regardless if they are contributing to rent. The rent has absolutely nothing to do with the situation.
I recommend she promptly find a new place to mooch so the actual tenant doesn't endure tenancy complications.