That isn't true. There is a nip that allow you delete stuff, but isn't implemented because of reasons. Just ask the nostr:nprofile1qqs9pk20ctv9srrg9vr354p03v0rrgsqkpggh2u45va77zz4mu5p6ccpremhxue69uhkummnw3ez6ur4vgh8wetvd3hhyer9wghxuet59uq32amnwvaz7tmjv4kxz7fwv3sk6atn9e5k7tcppemhxue69uhkummn9ekx7mp069f2j4