Duas etapas:1. atualize os registros com as localizações corretas, 2. exclua os registros com as localizações erradas.
update mytable
set onhand = onhand +
(
select coalesce(sum(wrong.onhand), 0)
from mytable wrong
where wrong.location like ' %'
and trim(wrong.location) = mytable.location
)
where location not like ' %';
delete from mytable where location like ' %';
