How can I remove support for insecure TLS ciphers?

Edit the Bastion configuration file. Append to the cipher string an exclamation mark and the name of the cipher you wish to disable.

For example: 
<allowedCiphers>

AES128+EECDH:AES128+EDH:AES:ECDHE:RSA:!aNULL:!eNULL:!EXPORT:!MD5!RC4!DES

</allowedCiphers>