In case you ever need to, it is possible to groom a table without taking a backup first. This can be useful if you have a transform that affects millions of rows, or if you are moving or updating large sets of data for any reason. This will reclaim disk space from the deleted rows.
groom table YOUR_TABLE_HERE reclaim backupset none;
Remember, if you’re deleting all the records of a table, it’s better to use truncate. If you can truncate, grooming is not necessary.