Is there any way to roll back a user action on the "on user input" event

Is there any way to roll back a user action on the "on user input" event

I have an invoiced flag on a subform, when this is checked the user isn't allowed to make any changes to that row. However, rows that don't have that flag checked can still be changed. Is it possible to cancel, or rollback the users change in the "On User Input" event?