Need some advice.

I have a tenant, the person that I bought the multi-family property from, who is being quite the pain.  When I purchased the house the tenant signed a lease converted to month-to-month in June.  Between January (when I took possession of the property) and June, the tenant caused the back door to be kicked in by the Fire Department because she left food cooking while she left the home.  I informed her that she would need to pay for the replacement of the door because of her negligence and then sent her a bill for the door along with receipts.  I had heard that the tenant was moving items from the unit over the last few weeks but never received written 30 day notice that she was moving.  I spoke with the tenant yesterday as it appeared that she was still moving.  I informed her that since she had not paid for the door replacement that it would come out of her security deposit.  She requested the remainder of the deposit be paid to her  I told her she would not be getting that either as she had not provided written notice per the terms of her lease.  Today is 7/2 and the tenant still hasn't moved out, has been washing clothes non-stop (running the water bill up).  And even caused an overflow or leak that has run into the unit downstairs.

What should I do?