If the Department of Education goes away, rich states can still spend lots of money on schools, but poor states might not have enough. That means some kids get great teachers, new books, and nice schools, while others don’t. The government helps make sure all kids have a fair chance, no matter where they live. Without it, some schools might get worse, and some kids might not get the help they need to learn.
Unfortunately we can see what is to come with state funding education departments separately. Propublica found Alaska's state gov. ignoring hundreds of requests spanning more than 25 years for primarily rural schools (aka typically poor or Native American/a minority). It bad enough the school buildings are condemned...
Don't worry, it's not just the schools with primally indigenous/ Native Alaskan attendants that have maintenance requests ignored for far too long. The only areas the state addresses non immediate issues in are Anchorage, Fairbanks, Sitka, and Juneau, all other areas are often be ignored because they have at most a couple thousand people.