Here's a link to Jawusa's tutorial on removing stealth subhoods:
https://modthesims.info/t/655536

If I'm not mistaken, now with the help of Jawusa's tutorial, one can remove every subhood type from a neighborhood - except for the last remaining university campus. (The game disallows it because otherwise, your young adult Sims wouldn't be accessible for play; despite you potentially not even having controllable young adult Sims in your neighborhood.)

In other words, it's possible to undergo Mootilda's tutorial on any neighborhood now, as long as:
1) you've removed the vacation destinations, suburbs and downtowns,
2) you've removed the stealth neighborhoods using Jawusa's tutorial,
3) and you have never added a university campus to the neighborhood (equivalent to having no young adult Sims in your neighborhood in a vanilla game).