There are 2 ways you can create a CTF which are explained here. There may also be times that you need to create CTF with no Destination School or Local Authority. The most common reason is that you are using the CTF to update a third-party system you may be using.
To create the CTF, follow the steps in the link above, but when prompted for a destination select one of the Unknown Destination options.
Once you have done this the CTF will now have a series of letters in the destination boxes and can then be accepted by the recipient as the destination is not defined.