Question about spellcasters and un-learning spells

I don't think you can un-learn spells. But I have never seen spellcaster cast spells autonomously.

Spellcasters won't cast spells autonomously unless they're gathering in the club where one of the activities is casting spells.

And don't worry about the Duplicato spell. It's one of the three ultimate spells (the others being Strangeify and Rite of Ascension), meaning that you won't accidentally learn it, but instead you must learn it from one of the sages (which one depends on the spell).

I never heard of a way to unlearn a spell. Perhaps you could check your sims' hidden traits to see if there is a hidden trait for learned spells.

Normally spellcasters don't cast spells automatically. The only spell I have ever seen a spellcaster use autonomously is a cc spell to upgrade object. My sims house ended up with all objects fully upgraded before I figured it out. I think I will remove this cc spell next time I play a spellcaster.

Yeah I don't think you can although I wish you could.
I had to remove my sims from a Spellcaster club because I hated how they kept casting spells I didn't want them to and e.g. got rid of curses I didn't want them to get rid of and fiddling with their transportation settings. Though I guess you can rather easily add the curses back with cheats but still. Ivan also managed to create a permanent clone during a club gathering I wasn't controlling though I kinda loved it and now refuse to use the spell again in case he disappears.

Thanks all, this is very helpful!