I found some of the event options if triggered before hand even after reloading some saves they cant be undone.
Like the game has persistent memory of some triggered events.
Try this;
1. Load a save in which the triggered event item you wish not to happen has not occurred yet
2. switch the built in cheat option
3. save exit
4. do the trigger event
5. see if the the built in cheat option has changed and if you are able too enable, disable it to the desired switch parameters.
6a. If you are able to (at this point the continue playing normally,)
6b. If not, save exit
7. See if the the built in cheat option has changed and is switchable to the desired parameters.
8a.If you are able to (at this point the continue playing normally,)
8b. If not, load an even earlier dated save as for step 1. and then follow steps 2-8 again. Until desired outcome.