Normally, the NPC witch has a 15% chance every 2 hours to appear on community lots. This simple mod lowers the chance to 5% every 2 hours. NPC witches do not do much when they appear. They also cause the game to freeze for a while. I did not want to completely prevent them from appearing, because you need to befriend them to become a witch.
You obviously need Apartment Life for this mod to have any effect in your game, as otherwise you would not have witches.
You can tune this mod yourself. Open this file in Sim Package Editor. There is one resource called "Tuning - NPC Witch" which contains quite a few lines with no labels. The important lines are 0x4 and 0x5:
Set to 15 by Maxis, my mod changes it to 5. This is the percentage chance the NPC witch will be summoned by the game.
Set to 2 by Maxis, my mod does not change this. This is how often the game tries to summon the NPC witch. "2" means every 2 hours, "3" would mean every 3 hours and so on.
In order to unrar this mod, you need the latest version of 7zip
This global mod modifies one resource in the objects.package file. Any other mod that modifies this will conflict with this mod:
Tuning - NPC Witch/BCON/Group:0x7F17187C/Instance:0x00001007