Canadian PR applying us citizenship

I am a lawful permanent resident of Canada and USA. On August 2009, when I tried to return US with US green card from Toronto Airport, I was interviewed by a US customs officer. Although he finally allowed my entry to US, he placed a note on my record (electronically, not on my passport):"must relinquish Canadian permanent residency before any future departure to Canada."

I am planning to apply US citizenship sometime next year. I am not sure whether the Canadian PR will jeopardize my application. For the sake of certainty, I would like to relinquish my Canadian PR. Could you please advise me the followings:

1. . Will USCIS deny my citizenship application due to the Canadian residency status?

2. What is the procedure to relinquish Canadian PR status?

3. Do I get an official letter / document to declare that my Canadian permanent resident status has been relinquished?

4. How long does it take for the whole process once the permanent resident card is received?

Happy holiday to everyone. Thanks very much for your time and valuable advice.

The US is kind of picky if you're applying for residency status here. They want you to actually be a resident of the US, and have intentions to stay and be resident. If you have on-going processes in other countries, they frown upon that because they think you're not really serious about being resident in the US, and they have been known to revoke status from people who do that.

Contact immigration Canada to find out where to send your PR card.