You can use a script in Options > Scripting to unset this data:
$unset(artistsort)
$unset(albumartistsort)
Or if you actually also want to delete existing tags from files when saving use $delete:
$delete(artistsort)
$delete(albumartistsort)
Alternatively you can also keep the tags but set them to the artist name:
$set(artistsort,%artist%)
$set(albumartistsort,%albumartist%)
Or maybe you want “The Beatles” still be sorted under “B” and not “T”:
$set(artistsort,$swapprefix(%artist%))
$set(albumartistsort,$swapprefix(%albumartist%))