I somehow by mistake marked my "Places" keywords (I have about 100 of them under the Places keyword) with the Person keyword checked - I probably used the "Convert Keywords to Person Keywords" by mistake. I now want to undo this. In effect, I want the opposite function of "Convert Keywords to Person Keywords".
Is there an easy way to do this other than:
Unfortunately, there is no supported way of unchecking the Person attribute, other than editing the keywords one by one. Using Metadata > Export Keywords and Import Keywords generally won't do what you want, since Import Keywords always creates new keywords with no photos assigned to them. (And in any case, the exported text file doesn't indicate many of the keyword attributes, including the Person attribute.)
Over the years, many people have complained about the lack of batch editing of keywords in LR, but Adobe hasn't added any such features. And it's not possible for a plugin developer to provide the functionality, since LR doesn't provide the necessary hooks. So please add your vote and opinion to this feature request in the official Adobe feedback forum: Lightroom: Better keyword management | Photoshop Family Customer Community