Our son is 20 and has been living with us in our apartment. His name is not on the lease because it was supposed to be temporary. 9 months later he is still here. Our landlord came over last night and said he had to leave that night. He's not on the lease so she says she doesn't have to serve papers and stuff. We are in Iowa. I talked to the police and they said without the actual eviction paper they would not remove him because he is our son and by law is considered a tenant because he has been living there.My husband(his dad) wants him out, he pretty much hates our son. So can the landlord just come over and say you must leave by 6pm tonight or does she have to file the paperwork and have the sheriff evict him?

The police were right. Once your son established any sort of residency, such as having possessions there or getting mail there or being there over 30 days, he is a tenant, whether he pays a dime or not, or has a lease. The landlord has to evict him.

If your husband wants him out anyway, and he is destructive, doing drugs, or doing violence against one of you, that's a different matter handled as a crime, in which the police charge him (with evidence) and you get a restraining order to keep him from forcing his way back in.

The landlord will evict basically all of you, if son does not move out on his own, so expect that to happen. No they can not just kick son out, but they can file eviction for allf of you for being in violation of the lease