Updating Metadata in PSE 12

If you can still see the old tag in other programs, that's because you have 'written metadata to files', otherwise the tags would only be known to your catalog.

You can get rid of the unwanted tag in PSE11 and PSE12:

Select all files with the unwanted tag in the organizer. In the right information panel, click on the button 'Modify IPTC information'. From there you can manage (edit, replace or add new tags) the data in the metadata section of your image files.

I just tried the process and contrary to what I thought, the existing IPTC tags are not shown when you click on the 'Modify IPTC' button.
You can select your files, nothing appears; I have tested that after you choose to delete the IPTC data, all tags are removed from the files. When you enter new tags, you are given the choice to add or to replace the existing tags. Does that help you ?

What works for me:

The tags are ok in the catalog, but there is one or several unwanted tags already written to files (in the IPTC section).

- I select the files with the unwanted tag in the organizer

- I use the IPTC dialog and choose to remove IPTC data. That removes all tags from those files.

- With the same files selected, I choose 'Write meta data to file', which copies all the valid tags from the catalog to the IPTC section.

The idea is to clear everything in the files, then use the valid tags from the catalog.

When you are going to try an important change not only to the catalog, but also to many files, the obvious advice is to start with a full backup from the organizer. Should anything go wrong, you could always get back to the previous state (catalog and image files).

Also, I would not try the 1000 photos the first time : maybe a test on a dozen or so images.

I am assuming that the tags in your files all come from the organizer, not from another software. My suggestion is based on the fact that the tags in the catalog are the only valid ones. I have run that process on much more than 1000 files.

Lightroom is more powerful for metadata management. The problem with the Organizer is that it can only read the metadata in the files at import time. With the above solution, you can update the metada in two stages : cleaning, then writing. If on the contrary you want to update the catalog from the files, it's not possible... unless you delete the files from the catalog and reimport them.

Lightroom has various ways to 'sync' metada between files and catalogs in both directions. Also there are many plugins to add functionality to LR. If you don't get a more precise answer in this forum, you could ask in the LR forum:

Photoshop Lightroom