Help organizing similar albums

Hey folks, I have imported the following (using -A and the existing tags):

drwxrwxr-x  3 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, Deborah Norman, James Gilchrist, Michael Chance, Stephen Cleobury"/
drwxrwxr-x  5 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, Deborah Norman, Sarah Fox, Stephen Cleobury"/
drwxrwxr-x  3 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, Deborah Norman, Stephen Cleobury"/
drwxrwxr-x  3 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, James Gilchrist, Jonathan Lemalu, Stephen Cleobury"/
drwxrwxr-x  5 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, Michael Chance, Stephen Cleobury"/
drwxrwxr-x 22 user user 4096 Dec 18 18:01 "Antonio Vivaldi, Choir of King's College, Cambridge, Academy of Ancient Music, Stephen Cleobury"/
drwxrwxr-x  3 user user 4096 Dec 18 18:01 "Antonio Vivaldi, King's College Choir, Cambridge_Academy of Ancient Music_Stephen Cleobury, Academy of Ancient Music, Deborah Norman, Stephen Cleobury"/

How can I reset the albumartist and move these into a single directory?

The best way is probably to remove these from your library database (beet rm) and then import them again as a single album (perhaps with beet import --flat to ignore the existing directory hierarchy).