Thunderbird Portable Huge 1gb cache??! How do I delete?

I use TB portable and it's pretty customized with keyboard shortcuts and filters. I'd like to use the same template on other computers, possibly with different email accouns on different computers, but when I delete the existing accounts, TB is still an impossibly big 1gb in size.

Is there any way to remove the extraneous data after I've removed the email accounts?