Hi,
I think this is the right answer to your question.
SOURCE : CIC
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I want to change my school or program of study. How can I change my study permit?
Post-secondary student
You may change your school, program, field of study or level of study (e.g. from the Bachelor level to the Masters level) without applying for a new study permit. You do not need to apply for a change to the condition of your study permit, either. You may continue to use your study permit as long as it is valid.