According to the Canada Revenue Agency (CRA), the owner of the mortgage may only deduct the interest paid on a property. Since there are 2 co-owners, you may only deduct your portion of the interest paid for the year on this property.
(Note: As an owner, you are the only one who can use the related interest expense to calculate your rental income or loss, even if someone else guaranteed your loan or mortgage. For more information, see Line 8710 – Interest and bank charges.)