In resque's sources (Job class) there's such method, guess it's what you need :)
# Removes a job from a queue. Expects a string queue name, a
# string class name, and, optionally, args.
#
# Returns the number of jobs destroyed.
#
# If no args are provided, it will remove all jobs of the class
# provided.
#
# That is, for these two jobs:
#
# { 'class' => 'UpdateGraph', 'args' => ['defunkt'] }
# { 'class' => 'UpdateGraph', 'args' => ['mojombo'] }
#
# The following call will remove both:
#
# Resque::Job.destroy(queue, 'UpdateGraph')
#
# Whereas specifying args will only remove the 2nd job:
#
# Resque::Job.destroy(queue, 'UpdateGraph', 'mojombo')
#
# This method can be potentially very slow and memory intensive,
# depending on the size of your queue, as it loads all jobs into
# a Ruby array before processing.
def self.destroy(queue, klass, *args)