Schedulable class has jobs pending or in progress

Abort all the scheduled jobs in the org

List<CronTrigger> listCronTrigger = [select Id, CronExpression, EndTime, NextFireTime, OwnerId,
        PreviousFireTime, StartTime, State, TimesTriggered, TimeZoneSidKey from CronTrigger
        where State = 'Waiting' or State='Running'];
       
System.debug('No of jobs: '+listCronTrigger.size());

If (listCronTrigger.size() > 0)
{
    for (Integer i = 0; i < listCronTrigger.size(); i++)
    {
        System.abortJob(listCronTrigger[i].Id);
        System.debug('Job details ::'+String.valueOf(listCronTrigger[i]));
    }
}

https://help.salesforce.com/apex/HTViewSolution?id=000004423&language=en_US