Yes, you can.
Thorncrest Outfitters is located right in the center of Tobermory town and they offer Kayak and Canoe rentals.
Also there is
lands end park Lands end park is a private campground but you can rent canoes/kayaks from them on an hourly basis, even if you are not staying in their campground.
Its always best to make reservation for canoe/kayak rentals beforehand, as weekends in summer gets very busy and you will not find any rentals available if you go in the last minute.