But he was and so I think the informations are correct, otherwise we had to delete many entries of former or dead producers

This isn't about deleting information, but updating it. When someone dies, you change words like "is" to "was". In this case you would simply add words like "former" to show he is no longer a film producer or studio chairman, and note that his company closed in 2018. All current information should remain, but it's not correct to say someone is a film producer if they aren't anymore or to say they're the co-chairman of a company that declared bankruptcy two years ago.

You can simply add any information in his biography yourself it's not locked

Oh, I could have sworn it was locked yesterday when I tried to edit. Well thanks!

Looks good now. I locked it. Thanks.