You cannot delete files from the Arweave blockchain. This would be contrary to its core mission of preserving an unalterable storage system.
Within Akord, you can 'Revoke files', which moves them from your 'Assets' tab in a vault. This would prevent anyone from renaming, moving, downloading or viewing the file.
The file would continue to exist on the Arweave blockchain, but completely encrypted and essentially useless.
Still, once a file is uploaded, regardless of whether it's revoked, it will continue to use your storage allowance.
Always carefully consider the nature of permanent storage before uploading files, as not all data will be suitable.