No. Please, do not delete anything in the storage subfolder. The pieces could be audited from the trash, and if you delete them, your node could be disqualified.
This is mean, that your node is unable to run a used-space-filewalker with this option to be enabled:
Please, disable it. To speedup a next run of a filewalker you may enable the badger cache:
This is a recommended setup for this node, since the lazy filewalker is failing.
This is mean that you enabled the badger cache already, so let it finish the scan. The next run would finish the scan faster.