The police cannot help you in matters such as these since it’s a civil matter. In order to get this person out, there has to be grounds to terminate her tenancy. Based on what you have described, you would have grounds to evict based on non-payment of rent. In order to serve a proper notice, you will have to know the amount of rent she was supposed to be paying, when she stopped paying, and her full name. If you have all this information, you can serve her with a notice of non-payment of rent which is a Form N4. This is a 14 day notice which advises her to pay the arrears or move out. If she does neither, then the next step would be to file an application with the Landlord and Tenant Board to go to a hearing and obtain an order for termination. The forms required to apply are Form L1 along with a Certificate of Service. All these forms can be obtained from the Landlord and Tenant Board’s website at https://tribunalsontario.ca/ltb/forms/. If you’re willing to negotiate an agreement with her to vacate the premises, there is a mutual agreement form that both you and the tenant would have to sign; it’s called a Form N11- Agreement to Terminate a Tenancy. This form is also on the Board’s website under the Other Forms section of the site.