Permanently Deleting Sythe Account

I've been a member of Sythe since I was very young. Created my account in Dec. '05.

Seven years later, I'm realizing that the username I chose wasn't the smartest one, and it is pretty close to my professional online identities. As a result, when my professional online identity is Googled, many of my old Sythe threads show up.

I'm not ashamed of anything I have ever posted or said, but it would be a bit strange if co-workers, or anyone ended up seeing everything.

I understand I can't change my username, but I'm wondering if there's anyway I can permanently in an attempt to get it not to show up on Google searches anymore (although I understand, it may take a while).

Appreciate any advice I can get,

Thanks.