It’s the applicant's decision what programs they choose to rank and which they don't rank. However, it's important to remember that applicants and institutions participating in a match enter into a CaRMS contract.
Including a program or applicant on submitted rank order lists establishes a binding commitment of a match result. Applicants are not obligated to rank all programs they have applied to.
The contract http://www.carms.ca/pdfs/2019-Applicant-contract-EN.pdf cannot be breached.
Match contracts are binding, breaches are subject to Violation Review: https://www.carms.ca/policies