Opening your crontab file and deleting the entry would be the adequate way. Or you might as well simlink the executable that's called by the cronjob to an empty shell script.
I created a duplicate (click here to see) for your question, and agree with your initial proposal. After testing, it appears Quartz will never execute a cron expression with a year above 2300.
I needed a valid cron schedule (? syntax not working in my system) which resolves real dates, but to be effectively "never". My current best solution was to pick the most recent leap year and see what day Feb 29th fell on. Feb 29 2016 was a Monday, so the next Monday Feb 29 is currently furthest away.