Your question is about cancelling the principal applicant then change the accompanying spouse to the principal, I suggest you to call CIC to find out 1) if you are able to make this change to switch, do not mention anything about withdrawal; have this done first only if it's possible to make sure that it doesn't impact your parent's sponsorship application; 2) then once the switch is done successfully, request to withdraw your undertakding for the accompanying spouse who would have been the principal in your original application and now being changed to the accompanying spouse.
Just remember, once your case is approved and transferred to local visa office, you will need to deal with both CIC - Missisauga and Visa office, it's much easier to get things sorted out at the sponsorship stage.
Hope the above helps!
Just remember, once your case is approved and transferred to local visa office, you will need to deal with both CIC - Missisauga and Visa office, it's much easier to get things sorted out at the sponsorship stage.
Hope the above helps!