After Google’s Penguin update, many common link building practices were made unviable, and even devalued the sites and keywords they once promoted.  Many sites that previously had top rankings for their industry keywords found themselves wiped off the Google map because of poor quality links and/or a Penguin “spam flag.”  If you noticed a sudden drop in rankings on or around April 24th and/or May 25th, you are probably impacted by Penguin.  Google also sent out unnatural link notices around those dates, so if you received one of those, you definitely have a problem.  If you received a notice from Google around July 19th, you can probably ignore it because Google admitted to sending out notices on that date by mistake.

This does not necessarily mean you have to rush out and start trying to remove all of your old links.  Removing links is a time consuming and frustrating process that you may not always have to do.  Certainly prioritizing those efforts to remove the links hurting you the worst is a solid strategy.  Deleting links should be a last resort, and not something you should do right away, and definitely not without doing some research first.

There are three reasons to remove links.  The first is if you received an unnatural link notice from Google.  The second is if you have any de-indexed links as these will hurt the most.  The third is if you received a Penguin spam flag, which as noted above, would come in the form of a drastic reduction in keyword rankings on or around 4/24/12 and 5/25/12. Despite which reason you have for removing links, the same approach should be used.

If you received an unnatural link notice from Google, it [...]