For what reason? Local Folders is a default special account for Thunderbird and cannot be removed. For one reason the Outbox is located in this account. Do you never intend on sent emails?

I have 3 accounts Private, Hobby and Office, I want to separate each account so the Local Folders where useless an waste place on my desktop.

You wrote "For one reason the Outbox is located in this account." just I looked in my hidden Profile, each account has its one "Draft and Sent" only the Local Folders had no "Draft and Sent".

Wasted space or not, it is default and cannot be removed. Click the pointer beside and collapse the folders to one line.

FYI: Outbox has nothing to do with Sent or Drafts. All outgoing email passes through the Outbox. Kind of why they named it like that. And please do not rename it. People rename it and then forget they did that and come back asking why they cannot delete the special account named Bob.