I rent a small multi-unit building. The main floor tenants’ lease states that they are responsible for the snow removal of the property. Now that winter has arrived, they are telling me that they are not clearing the snow and that it’s not their responsibility. Is this true?

Yes, this is true. The landlord is primarily responsible to maintain the common areas of the property if it contains multiple units, and that includes clearing snow and maintaining the lawn in the summer months. Tenants are responsible for clearing snow and ice from areas used exclusively by them pursuant to s. 33 of the RTA, which makes tenants responsible for ordinary cleanliness of the rental unit.