Legally they have to tell you to delete all copies you have of it, but it's rare for companies to actually check, and they usually consider removing the torrent as sufficient. You should probably delete the file from the seedbox just in case.

As someone already answered your question, i'm more interested in your seedbox choice. Isn't your case (DMCAs) exactly why people get a seedbox to avoid these copyright infringement from your ISP?

Am I missing something here? I have never had a seedbox so I probably do, or this seems rather a bad seedbox in a bad country I guess?

Sorry for my ignorance if that's the case, but it's the first time I hear about a seedbox that states about copyright complains.