She has a lease--its an 'at will' lease. Give her 30 days written notice of termination. If she fails to leave, you will have to take her to general district court on an unlawful detainer action (eviction). You can do this yourself, no lawyers required. HOWEVER, if you do it wrong, the judge may throw out the UD and make you start all over. Speak to your county clerk at the GDC.
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