[2020] No Nag Mod

You mean the white box that shows on the left of the screen? Or chirps?

Both can be disabled without mods. Just go into "Options", and then under "Gameplay" find the "In-game settings". Disable "Show in-game guide popup" to avoid seeing the white box with tips, and disable "Auto-open Chirper messages" to ignore what your citizens are chirping about.