Hi an dwelcome tank! We are here because this is where our true family is. The people here were here for us when we were going through the awful times, whether with a difficult child child, difficult child sibling, difficult child parent, or just hard times for other reasons. The peopple here understand, do not judge or throw stones, and are not afraid to give us a swift kick in the pants when we need one. They also are people we honestly and truly care about. New people are treated this way because we were all new once.
You need to start working with your own therapist. Find one that you can like and who can understand what you are feeling and work on why you haven't followed through in the past. You have taught your daughter that you do not mean what you say so she doesn't have to do anything because you won't do anything. You have to work out why you couldn't follow through so that you can start teaching her you will follow through. It isn't going to be easy.
I am behind the idea of changing the locks. Or the idea of "renovating" so that she will find the home unlivable. What do you do that drives her totally nuts? Blast oldies on the stereo, sing loudly, cook things taht she doesn't like to eat, spray perfume that you like and she hates, keep the temperature too hot or cold for her and put a box over the thermostat so she cannot change it (the way restaurants do), paint it a color she hates, never have anything she likes to eat, whatever you can think of. Even buy pads instead of tampons if she hates them. Whatever you can do to make her unhappy and uncomfortable. I don't know if local businesses let her buy things on your tab, with the understanding that you will pay for them, but if any do give them a letter informing them that you will no longer pay for anything that she puts on your bill, from the date of the letter. Stop buying things for her. Keep food that you like and anything that she might take in a room with a deadbolt on hte door. Keep it locked at all times.
Start calling the police if she damages anything or brings home drugs or comes home stoned or does anything that is even a minor legal offense. The goal is to make home as unappealing as possible as much as possible. Heck, why not make sure the circuit breakers are in a room with a sturdy lock on the door and flip the one to her room "by accident" periodically when she is in there. then do n't tell her what you did.
You do have to explore what the legal options are. There is a possibility that you will have to evict her legally. If so , do NOT start court proceedings if you will not follow through. the absolute worst things you can do is to threaten something and not follow through with it. If it comes out of your mouth or you write it down and give it to her, then you have NO choice no matter what she does. You have painted yourself into a corner and have to follow through. IF you can follow through, file the papers with the court. A google search on tenant rights and/or talking to a lawyer to see if an adult child has t eh same rights as a tenant even if they don't pay rent is the best way to make sure you know your options.
Get creative, be ingenious and think about what she HATES the most. Then make home so uncomfortable and strict that she wants to leave. If you have to clean her room and remove everything that she did not buy with her own money and was not given to her explicitly by you or someone else after she turned 18, take it out of there. Call the police if she has anything illegal in there. If she damages ANYTHING in your home, press charges for vandalism or destruction of private property. If she is violent with you, call the cops and press charges for domestic violence.
If she has been violent in any way with you, or abusive in any way, even just verbally, get to a domestic violence center and get help. It will be free most likely and they will be able to help you figure out why you tolerated it from her, and how to stop it now. If she is violent with you now? You call the cops. Violence can NEVER be tolerated and needs a very strong, strict response. If the cops take her even for just a night, get a restraining or protective order as her victim. it will mean she cannot contact you or come onto the property of any of your homes. It can be done after hours by calling an offficer and asking how to do it. This will force her to move out or spend time in jail. Again, if you won't do it, don't say you will. It will make things vastly worse very fast.
I hope this helps. It may take a bit of time to truly be able to follow through, so be patient and kind to yourself. No one deserves it more.