A few years ago I had very little credit history and my parents agreed to put me as an authorized user of their cards to help build my credit. I've since built my credit significantly and my parents had some financial troubles that caused their credit card debt to increase significantly. Concerned that this would affect my credit score, I called and had myself removed as an authorized user on these cards. This was about 5 months ago. However I just checked my credit report and they still show as open on my report even though I'm not an authorized user of that card anymore. How long will it take for these cards to be removed from my report?
You may have to call the bureaus to have it removed or file a request. However, any accounts that are in an open status will remain in an open status until they are closed.
So, the most likely case here is that the bureaus aren't updating your authorized user status. And, it's not unreasonable to think that they won't ever do so, as long as the account is open.
If you're concerned about this particular account having an adverse effect on your credit score, I'd suggest reaching out to the bureaus and filing a request.
For instance, here is Transunion's dispute page...
Experian and Equifax have similar processes.