Several states came in when they did to balance slavery. Without slavery harder to see Maine, and of course West Virginia.
If NY is adamant about Vermont, then Vermont stays independent and not a state. If the Georgia govt wasn't corrupt and inept in selling Yazoo lands then Georgia doesn't sell to the Federal govt the northern half of Mississippi and Alabama. Mississippi and Alabama ends up as one state, as just the southern half of the two, and probably gets more of the Florida panhandle.
Delaware shared a governor with PA until 1776, could end up becoming part of PA instead if an arrangement can be made with Maryland to offer them something as compensation.
North Carolina didn't have to give up Tennessee.
Virginia could keep Kentucky with a POD during the Articles of Confederation.
Northwest Territory had two possibilities by Madison- 5 states as we have now, or 3 states (Ohio, Indiana, and Illinois extended north to Canada).
Can't see a united Dakota since Oklahoma, Kansas and Nebraska borders were placed there specifically for each state to be the same height. And if it wasnt for the North and South names would anyone even keep proposing they could be one state? Anyone ever propose Nebraska and Kansas be one? (Which is just as likely as the Dakotas)
To have no Alaska you have to have no Hawai'i. They were brought in as a balance. Alaska was thought to be Democratic, and Hawaii Republican (ends up they became the reverse but still a balance). Both territories were on the UN's list of non-self-governing territories and the US had to find something to do with them. Only if there is no Cold War could independence or continued defiance of the UN be an option. As long as they are strategic and the USSR so close they have to become states. So, yes you can get rid of them, but the PoD would have to actually have nothing to do with them, you're messing with other history and they'd be a side effect to get what you want.
Montana, Idaho, and Wyoming were proposed as two states, the area divided horizontally.
No Mormon religion means a larger Utah, possibly no Nevada, as the western part of Nevada goes to California and Utah keeps the many slices taken over the years for Nevada to be larger.
No Gadsden Purchase and the larger Utah described can result in New Mexico including Arizona (and probably Las Vegas).
No Mormons and larger accepted Utah, could find a way to stop the extralegal Jefferson Territory, and Kansas is able to hold on to the west farther than OTL.
Oklahoma could remain a huge Indian Reservation.
I'm thinking I found enough things to eliminate about 15 states but only by fundamentally changing history. Very few states can be eliminated as easily as "Congress and the people in that state decide not to be a state". Most states non-statehood would have to be eliminated as a side effect of a Greater part of history changing, or effecting a second or third state before, at the same time, or after it. Missouri had to wait almost a year for Maine for instance before becoming a state (Missouri state seal has the wrong date on the emblem because of this)