Did you claim the deemed disposition in 2015 when you first started claiming CCA? Since you are no longer renting the property, are you trying to change the use to a principal residence from an income property?

We bought the property in 2015 and started renting a month in.  So on 2015 return we claimed CCA and rental income.  I was not aware I had to claim home purchase.  Yes, it has been a full principal residence since December 1, 2016.