Which of these Lightroom catalog files is ok to delete?

Looking at the modification dates, the first catalog in this list is your current catalog. All other files with the .lrcat extension have not been used for at least one year. Be very careful however, because the second file in this list has the exact same name! That means there is an old copy of your current catalog somewhere in another folder, so make sure you don’t delete the wrong one. That old copy is probably in some ‘old catalogs’ folder, that was created when Lightroom Classic upgraded this catalog. Lightroom no longer renames the catalog on upgrade, so this is the old version from before that upgrade.