According to section 27 (2) of the Residential Tenancies Act, the landlord is not required to be present during showings to prospective purchasers provided the landlord has given written authorization to a broker or salesperson registered under the Real Estate and Business Brokers Act, and written notice has been given to the tenant at least 24 hours before the time of entry to allow a prospective purchaser to view the premises.
For more information, review our RTA fact sheets entitled Selling a Rental Property and Entering the Rental Unit at https://landlordselfhelp.com/rta-fact-sheets/.