Get your ftp login credentials from your host and delete the theme via ftp.
You don't know who the host is? Is this your website, or one that you're working on for someone else? If the latter, you'll need to have them obtain the ftp credentials.
Get your ftp login credentials from your host and delete the theme via ftp.
You don't know who the host is? Is this your website, or one that you're working on for someone else? If the latter, you'll need to have them obtain the ftp credentials.