user\mods, BepInEx\plugins and/or BepInEx\patchers.BepInEx\plugins\spt folder and BepInEx\patchers\spt-prepatch.dll file.Nearly all mods can be added to an existing profile. However, removing some mods might be impossible without making a new profile. Mods that add new traders, quests, or items fall under that category. Always read the modpage, as the author should specify if a mod is unsafe to remove from a profile.
If you removed a mod that broke your profile, SPT can try fixing it. This is not guaranteed to work. SPT will do the best it can to remove any item that’s in your profile from the removed mod, but some mods make irreversable changes to your profile.
SPT_Data\Server\configs\core.json in a text editor.removeModItemsFromProfile from false to true.removeInvalidTradersFromProfile from false to true.The above should be viewed as a “last resort” solution. Even a profile “fixed” by this method can exhibit issues like random crashing, bots not spawning, and some maps being unloadable.