You can uninstall or removes an installed jackd1-firewire package itself from Ubuntu 16.04 LTS (Xenial Xerus) through the terminal,
$ sudo apt-get remove jackd1-firewire
If you would like to remove jackd1-firewire and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove jackd1-firewire
If you use with purge options to jackd1-firewire package all the configuration and dependent packages will be removed.
$ sudo apt-get purge jackd1-firewire
If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.
$ sudo apt-get purge --auto-remove jackd1-firewire