As per the CRA: Commission employees can deduct the cost of a training course as an employment expense. The course has to maintain, upgrade, or update your existing skills or qualifications that relate to your employment.
You can't deduct the cost of a training course if the course is for personal reasons, the cost is unreasonable, or you receive a lasting benefit from the course.
If you can't deduct the cost of a training course as an employment expense, you might be able to claim it as a tuition amount.