It is an offence under the Residential Tenancies Act for a tenant to change the locks and bar the landlord’s access to the rental unit. A landlord may write a letter to the tenant requesting that the chain lock be removed. If the tenant does not comply, a landlord may contact the Rental Housing Enforcement Unit of the Ministry of Housing at 416-585-7214 or toll-free 1-888-772-9277. They can notify the tenant that he/she is committing an offence under the Act and can be fined.