This is mentioned on cic.gc.ca
Post-secondary student
You may change your school, program and/or field of study 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.
If you are changing your level of study (e.g., bachelor’s to master’s), you do not need to apply for a change to the condition of your study permit, either.
What if i change my program from 3 yr diploma to 2 yr?
Post-secondary student
You may change your school, program and/or field of study 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.
If you are changing your level of study (e.g., bachelor’s to master’s), you do not need to apply for a change to the condition of your study permit, either.
What if i change my program from 3 yr diploma to 2 yr?