How do I combine music libraries?

New user here. I added several large music collections from 1 external hard drive. Because I linked to them at different times, they show as 3 separate libraries. I want them all in one library. How do I combine them?
Thanks

You can delete 2 of them and add the underlying folders as extra folders to the 1st library.
https://support.plex.tv/articles/200289266-editing-libraries/

First, I see nothing in the edit screens for deleting a library.

Second, when I used the “Add Folders” prompt, I ended up with separate libraries, even though I used the name of the first library when attempting to add the new folder.

This is not clear at all.

as for how to delete a library, follow the instructions of this support article. There’s a Delete menu item in each library’s context menu:
https://support.plex.tv/articles/200289286-deleting-libraries/

For the remaining library… by hovering over the library, clicking ... > Edit you will be able to modify the folders Plex will associate with that library.
Based on the picture below…

  • click the x next to a folder path to remove that folder from the library
  • click Browse for Media Folder to look for additional folders (and add them) – This will not create new libraries but add the content found in the newly added folder(s) to the given library.

Thanks