As per the office of the CBC Ombudsperson, "it is CBC policy not to remove or alter archived stories other than in the most exceptional circumstances. If a story is inaccurate, we will correct it and advise readers that we have changed it. If relevant new information emerges, we will update or write a follow up story. But once published, the story is a matter of public record. To simply remove it, or part of it, from the archive would take us into rather treacherous waters. Selectively changing or removing stories, however good the reason seems at the time, is in effect censoring them, altering the past."
For more on this position, here is a review from the office of the Ombudsperson that goes into detail about a particular request, and offers further insight into why it is not possible to remove stories:
As well, here is CBC's written statement under transparency.
We will update a story when new information becomes available. If you have new information about a story, you can send it, along with the appropriate URL, to CBC Audience Services.