Yes, you can leave Canada with your Indian passport without issues. However, you can't come back to Canada without a Canadian passport. You can carry your citizenship certificate and apply for a Canadian passport in India. However, my comment was about entering the country with one passport and leaving with another.Finally got through BLS call centre, agent advised if I travel with Indian passport, I will have to pay a penalty/fine later when I surrender passport.
Agent also said passport surrender process and visa/OCI application is independent. I have to do both, but OCI will be processed in 5-7 weeks and won’t be delayed awaiting passport surrender process.
What you can do is this (this was posted somewhere on the forum and pointed out to me by a friend of mine).
Travel to India on Indian passport > Do NOT reveal about your citizenship > Apply for a Canadian passport > Get a visa to Dubai on your Indian passport > Exit India with your Indian passport > On arrival in Dubai, show your Canadian passport and get a visa on arrival > Book a ticket from Dubai to Toronto (or any other Canadian airport) > Show your Canadian passport when leaving Dubai > Come back to Canada.
Once you are in Canada, you have to pay a penalty to surrender your Indian citizenship and can then apply for OCI.