`bjobs` can list just the pending jobs with `-p`. It would be nice if `bkill -p` would also filter jobs, so `bkill -p 0` would kill all the user's pending jobs.
The best I can think of is some shell magic. While not perfect, it should cover many cases. e.g.,
bkill `bjobs -p -o id -noheader | tr '\
' ' '`
`bjobs -p -o id -noheader` lists the job ids of the user's pending jobs. `tr` will put it in the format that `bkill` expects. One potential problem is that if the job list is too long then the max command line length or max number of command line arguments will have been exceeded, so bash will complain.
There's a small race condition here. A job could start between the query and the kill.