Remove all scheduled jobs/CronTrigger tasks

cronUnscheduler.java

List < CronTrigger > listCronTrigger = [select Id from CronTrigger LIMIT 150];
If(listCronTrigger.size() > 0) {
    For(Integer i = 0; i < listCronTrigger.size(); i++) {
        System.abortJob(listCronTrigger[i].Id);
    }
}