Troy - much the same as the question for your merge agent:

sp_help_job will do it on an ad-hoc basis, but if you need to do something
as a result of the job status, you could modify this script to do it:
http://www.replicationanswers.com/Downloads/KillRunningJobs.txt
    Cheers,
         Paul Ibison SQL Server MVP, www.replicationanswers.com .