jjlists123, the only solution now would be to follow Kirk's advise. This, however, removes all your keywords, perhaps also the ones you'd like to keep. Currently there is no alternative within PM though.
I'm sure that with the implementation of the "catalogue" function in PM this will be possible more easily. But that version is still in the making.
If you want, you can accomplish the same thing with Lightroom, you could download a test version and use the 30 day trial period to test this. Be sure to sync the XMP/IPTC within PM after you've updated the info in LR (and set the preferences to XMP sidecar first, followed by Embedded XMP, and Embedded IPTC).
Cheers