You can find this tool--once it rolls out to you--by clicking on the "Photos of You" tab, selecting multiple photos and then choosing the option you prefer: untagging all the photos or requesting that the photos be removed. You also have the option to include a message to the person who posted the photos.
Naked Security's Vaas says this change, while a step in the right direction, misses the mark:
"Rather than having to slog through a continual process of requesting that people untag them in photos, and that they please leave off the habit entirely in the future, and rather than simply blocking tagged photos from appearing on their timelines, many Facebook users want to simply block anyone from tagging them without having received express prior permission to do so," she says. "Unfortunately, Facebook has failed to give us this blanket tag-blocking ability in these recent privacy changes."