Sooo, I exported my story progression settings from my main neighborhood and when my sim went to college I imported the settings that way I didn't have to mess around with it. Annnnd I think I majorly messed things up because now I have kids running around and living in the college neighborhood. I didn't think this would cause a lot of problems but sometimes when my Young Adult Sim is in class the whole class will reset to outside the building and it shows him skipping class. My game has crashed a couple times. Also I keep getting a notification that the town is actively encouraging immigration but there is no room in town to move into (something like that).

I ended up going back into story progression and reset all settings. Then I went into Master Controller and reset everything for good measure...but still having issues and don't know how exactly to fix it. If my Sim moves back to the main neighborhood will the college reset? sorta?

Drats, I thought you were going to tell us that you were seeing children actually enrolled in degree programs at Uni. Not just living in the world. That would have been cool, although of course not intended.

Pregnancies can form in Uni World. Typically we would see such pregnancies resolve into children on a next visit as the world's demographics doesn't really favor babies or toddlers. The same is true for the WA worlds. But it's also possible that you have been running SP with immigration on from using your imported homeworld settings and new households with children, which would by typical of a homeworld, are arriving at Uni World to take up available housing. There's nothing inherently wrong with children and teens living there, although unless you have placed some there would be no schools for them to go to.

Not sure I understand why the confusion over immigration being activated until the point where all available houses were used up if those were the settings you had in the imported SP options. To turn immigration off entirely, NRaas > SP > General Options > Options: Lots > Options: Immigration/Emigration > Immigration Gauge > 0. Use an in-game computer or the Admin Bldg (standing in for City Hall) to reach General Options in Uni World. It's fine to run SP in Uni World, but many of us wouldn't want ALL default settings applied there because it's not a typical homeworld and some of them that make perfect sense elsewhere won't really give us what we want here. Another example is with careers. If you allow SP to push careers as it might in a homeworld, and you place one rabbit hole lot for other reasons (let's say you wish to have a hospital or a new bistro in town), the entire world might try to get jobs there because other than being Uni Students or becoming street performers there aren't many jobs for them to take up.

MC doesn't have anything to do with how a world progresses or not. It is merely a player controlled command center.

If you want to drop out (return home) and try again later, the way to revert Uni World back to the way it was the very first time we all see it, including with the same local sims at their original ages, the way to do that would be once back home, pull out the Sims University nhd file from your current save. The next time you travel to or enroll in Uni, a fresh instance of Uni World will spawn. Note that all of the original sims as your sims may have already known them will be gone if you do it this way as they would have been replaced with first-run copies. Alternatively, you could revert to a save from before anyone left for Uni this time and try things again a different way.

Make sure you have Overwatch and ErrorTrap in place if you yank the nhd file out or things won't be pretty.

Ok, I think I'm going to just disable SP on all worlds except the main neighborhood lol.

Is there a way to remove all the kids so that it's only college enrolled sims living there?

You can use MasterController to totally annihilate them, we won't judge you.

There will usually, in my experience anyway, be some local town residents who are not enrolled in Uni. Or at least not all of them enroll every term.