You should always attempt the RELEASE MLOAD before you drop anything. That way if you get 2572 you can decide if you want to restart the MLOAD and allow it to complete or if you really want to abort it and leave the table partially updated. You no longer have the choice of restarting the MLOAD and allowing it to complete.
You can use SELECT with an ACCESS lock to copy the contents to a new table. Or if the table is very large and you need to re-enable full access to the partially updated table without copying it, you will have to RELEASE MLOAD IN APPLY, then DROP all secondary indexes, if fallback-protected then ALTER TABLE NO FALLBACK (then ALTER FALLBACK again if desired), and recreate all secondary indexes.