I requested removal from Quora last week. 27 hours later someone from user operations emailed me confirming it was done. Perhaps they did improve the process recently.
I then contacted their customer service to find out why it hadn't been deleted. Their customer service team was responsive and helpful, and it was deleted within 24 hours.
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We’ve deleted your account information from our end.
However, if you are already in a search engine like Google’s search index, they won’t know to drop you from it until they try to re-crawl your page, and unfortunately we don’t have any control over when that will happen. The best thing to do in the meantime is to directly request removal from Google itself here: https://www.google.com/webmasters/tools/removals. Once you have submitted your request(s), you will need to wait for Google to reindex the pages — this often takes a few days.
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Right now, I am only aware of the Google webmaster tools where you have to input each individual link you want removed, and even that request is queued and takes time, with no guarantee that they will reindex the content.
If they send you all info that they have about you, that doesn't prove that account has been removed, it only proves that they have all your data.