The Residential Tenancies Act applies to the landlord-tenant relationship regardless of whether or not the rental agreement is in writing. You should send the tenant a letter outlining the issues that you mentioned and request that it be corrected. If they do not comply you may serve them with a Form N5 Notice to Terminate a Tenancy for damaging the rental unit. This form can be obtained from the Landlord and Tenant Board’s website at https://tribunalsontario.ca/ltb/forms/