Use the scancel command to kill your jobs.
scancel -u chris
Will kill all jobs for user chris (you can only kill your own jobs).
scancel NNNNNNN
Kill a specific job. Get the job number from squeue, or from the output of job submission.
Note: It's scancel not skill. skill is a command available on Linux but is not part of SLURM and will not kill your SLURM jobs.