Hello gpb56,
Glad to have you join the QuickBooks Community. I'll be happy to share more info about reversing a stale outdated cheque using QuickBooks.
If the cheque in question wasn't cashed as described, or included in previous reconciliations, you can delete it using the steps provided in this helpful article here. However, if the cheque was reconciled you'd have to undo the reconciliation first then follow the steps in the article to delete it.
Let me know if this info helps. I'll be here in case you have other questions.