In cryptocurrency, you are responsible for securing your private keys. That's not anyone else's responsibility. Have the keys been changed or do you still have access to the account? Have you looked through https://steemd.com/@jadabug to see when things changed? Have you checked to ensure the account wasn't connected to something on Steemconnect that may have been compromised? https://app.steemconnect.com/dashboard

A blockchain is forever, so there is no way to remove content from it. This account, if not controlled by your daughter, is not your daughter, so all you can do is create another account that is her and make it clear which one is real and which isn't from the new account.

Calling the blockchain "a den of thieves" is not an accurate statement. Everyone, again, is responsible for managing their own private keys. If they were compromised, you should figure out how and take steps to avoid that in the future. I've been trying to help people for years understand this stuff with posts and videos like this: https://steemit.com/blockchainfreedom/@lukestokes/understanding-blockchain-freedom-episode-003-safety-and-security