Can I Delete Reticulated Splines Sims 4?

It can be safely deleted.

Can you delete Localthumbcache Sims 4?

Whenever you make a change to your Mods folder, you should remove your localthumbcache from your /Sims 4 folder. Some players choose to delete it everytime they close their game, others choose to only delete it when necessary.

Can I delete Lastcleanexception Sims 4?

@YsUniverse Yes, you can delete those files. They're reports of in-game errors, so they're useful for troubleshooting purposes. ... However, the game itself doesn't need the files to be present.