How to remove facial tags on Lightroom?

Hi,

I'm trying to catalogue my photos by person. I can't find a way on Lightroom 3.1 to delete all faces from particular photos e.g. blurred crowds in the background. This results in lots of random photos appearing in the keyword information for a person. I've only found a way to individually manually untag a person from a photo, but not to delete the tag altogether, and also not to untag en masse. This used to be possible on Lightroom Classic, as indeed it was possible to do the oppositie and create a facial tag - but I can't see any functionality to do this on LIghtroom 3.1.

Many thanks for your help

Andy

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