I've recorded a video to explain why this is happening and what the immediate solution is so that you can get on with your work (for you to become a top level admin too, and then you have to edit these directly under CONTENT > A-Z DATABASES)
There is a much bigger issue to resolve so that your A-Z list is useful to patrons, easy to manage, and so that librarians can edit their links within your guides and not have to go this route - the following instructions for that are more meant for George :)
2. Review all the records and grab from the first column all the IDs of the assets that should *not* be in the A-Z list. Send me that list of asset IDs in a comma separated list (ex.: 1111,11112,11113,11114,11115) and I will run those through a utility that will take them out of the A-Z list repository (which only admins can edit), convert them into Link Assets and put them in the CONTENT > ASSETS repository.
3. Now we should have a far shorter list of Database Assets. We can then work on getting all duplicates removed from there and replaced with mappings to a single parent record for each database. As I mentioned in the video, we'd be wanting you to define which of the multiple links to JSTOR should be the authoritative one, and then make the others become mapping instances to the parent one.
I hope you're with me so far :)
It's going to be a big project to go through 6K+ records, but we'll be glad to help you with the most tedious part of the process (putting things in the right repository and replacing duplicates with mappings).