Unresponsive process

pkill -9f process-name

Example:

pkill -9f filezilla

If you have launch a command that you cannot directly stopped with usually ctrl+c, you can always put the process in the background with ctrl+z and then use the jobs command to list the job (command) that you have launched. Then, you have the number of the job and you can kill it with the command kill %<number_of_the_job>.

Example:

$ sleep 100
^Z
[1]+  Stopped                 sleep 100
$ jobs
[1]+  Stopped                 sleep 100
$ kill %1
$ jobs
[1]+  Terminated              sleep 100
$ jobs
$