I moved my ex wife back into my home which I own, she has been living with me and our children for the past year and a half. She has started her old patterns of staying out and not coming home which is why we divorced in the first place. I have custody of our children. She has been contributing towards bills, but yesterday I found out that she was looking for an apartment and has stopped contributing. She does have mail come to house, but what can I do if any to kick her out or tell her to leave

You say you "own" the home. Does your ex-wife have an interest in it as well? If you purchased it while you were still married then she probably does, assuming that you're in a community property state. Now, if she bought you out at the time of the divorce or you purchased it on your own after the divorce, then that's different and she has no legal interest in it. And if that's the case, then in order to get her to leave you'd have to go through the eviction process and this varies according to jurisdiction. She's been living there for a year and a half so that is her legal residence so an eviction is the only way to get her out if she doesn't leave of her own accord.

If she's already looking for an apt. why do you need to evict her?

I was about to ask the same thing, what's the need to evict her if she is planning on moving out? Assuming that she has no interest or stake in the house, and that its completely yours look up eviction laws in your state, here I believe it's 30 days.

I guess your really upset with her and just want her out asap. I know that feeling because I went through that with an ex roommate/friend of mine. Since you already know she is leaving, as Chuff mention, why don't she help her out with her apartment hunting? Two heads are better than then one and the sooner she finds a place the quicker she will be out of your hair.

Leave an eviction notice on her bedroom door.