About the event

Not sure what you mean. If you started a social event, you can end it in the top left corner. If it’s a holiday from Seasons, you can edit your calendar to change or remove holidays. If it’s one of the various festivals in several different packs, your sim doesn’t have to attend.

Does any of that help?

I don’t think you’ll ever be able to keep your sim’s emotions from changing though; almost everything in the game is tied to moodlets.

It's a bulk delete. I wish they'd let me choose whether the event occurs from the game options. Deleting it from the calendar is just too much work. What's more, it's a problem that it changes the Sims' emotions.

If you never want to play with holidays in any of your saves (and don’t want to disable Seasons) then I would recommend you make a starter save. Create a new save, go in once and delete everything off the calendar, then save it as “Starter” or “Template” or whatever makes the most sense to you. Then from then on, whenever you want a “new” save, just open the starter and immediately use “Save as” to create a save that already has the calendar emptied.

Thank you for the information.