Edit: fml I didn’t see it’s already there but collapsed under “Advanced Troubleshooting”
The Knowledge Base article about resetting the UI should include this console command because renaming/deleting the WTF folder will not reset all CVars.
/console cvar_default
For example disabling the Sticky Targeting option deselectOnClick and then exiting the game and deleting your WTF will not reset it.
Those can still be reset with the “Defaults” button, but which does not reset any CVars not tied to an interface option, so using the command would reset everything.
Customer Support also suggests using this for resetting the UI.
https://wow.gamepedia.com/CVar_cvar_default