If your plan is to sell the house there is not a notice you can serve the tenants now before putting the house on the market. You can only give them notice to leave once you have a Purchase and Sale Agreement signed and the purchaser is planning to live there. The only thing you can try is asking them if they would be willing to move out so that you can do the repairs in order to sell. If they agree to move out then you should have them sign an agreement to terminate the tenancy which would be Form N11. You can obtain this form from the Landlord and Tenant Board’s website at https://tribunalsontario.ca/ltb/forms/#landlord-forms.