Amortization calculation of Liab & ROU when not exercising future open option.

As part of our IFRS16 phase 1 testing, we created a 1 Year lease, with a 1 Years future open option included. The lease detail report is correct in that the LIAB & ROU Amortization is correctly calculated i.e. strait line amortization. We now 2 months before the end of the initial lease decide not to take up the option, we cannot cancel it, as that will remove the option completely out of the equation, What we want to see is that the amortization calculation stays the same as before until the date of amendment of option