this is the basic expression:
BUT: if you delete the ALBUMARTIST you will get problems on most players in respect to grouping albums together.
Also, I would use a filter as this means that only the hits are treated and not every file get evaluated.
And then it is even simpler to remove fields.
So, to get rid of a field:
Format value for ALBUMARTIST
Format value: $if($eql(%artist%,%albumartist%),'',%albumartist%)