You can revert your document to the last saved version, or (if you have the Enable Rollback and Crash Recovery File Preference option set—page 188), restore it to a particular point in time since the last save. This is useful if you find you have made some catastrophic error, such as posting heaps of incorrect transactions or inadvertently deleting all your customers.
— Page 22 of the MoneyWorks User Guide
You can rollback your transaction if you have not exited your MoneyWorks’ document (Company file which you are working on).
Assuming you had accidentally posted a transaction and you wanted to undo the posting, you may use the Rollback “Company Name” function from the File menu to rollback your last entry.
A Rollback Changes window will be popped up showing a list of transactions which you had recorded since the last save.
To undo the last entry, Post Transactions, you simply click on the entry (this entry will not be highlighted) and click the Rollback button to rollback your transaction till before you posted the transaction (Note: those highlighted transactions are the transactions which you wanted to keep).