OK I'll bite, to get a new identity you don't need to leave the country... if you know people that know people you can just, get a fake SSN and a Green card(alien resident card) which gives you "legal right to work in the US" when they ask why you have a green card yet speak English with "american" accent and everything, you can tell them that you were born in another country but were raised here and you just applied and were granted a legal resident status. You get these 2 documents with the fake name and this the easy step. Now you have to claim another country as your own.
Depending on your race I'm sure you can find online many people from Caribbean/South American Countries that can make you and mail you an "official" birth certificate and passport from that country, hell you can probably get a visa too, not fake made in a home computer, real ones from the government, corruption it's so bad they'll do anything for money. If you can only get a birth certificate and nothing else it's ok, you can take that "official" birth certificate to the consulate from that particular country here in the US and ask for a passport, most consulates will issue one. make sure the documents from the other country match your fake SSN and green card.
After you do that I'll travel to one of those states that does not ask for SSN when getting a license... at this moment I believe are New Mexico, Utah and Washington, North Carolina used to be one of them, I don't know if they still do or not.
If you don't want to travel or are too far away from any of these states you can just go to the SS office that is local to your home address and ask them for a letter of 'non-issuance'. This shows that you are not eligible for a valid SSN but are "legally" here with Passport/visa/permit. At the SS office I would only show the birth certificate from that other country and or passport/visa permit, this 'non-issuance' letter is used to get DL by people who entered the US legally, you take that letter to the DMV along with your passport/visa/permit and then and all you have to do is take the test.
Once you have the DL is time to get away I would move to a big city like Dallas, Houston, Atlanta, LA or New York where I won't stick out.
All this is if you want to have a regular job and a regular/modest way of living, most entry level jobs won't check to see if you SSN is fake and once you have your license you can just use that as the ID instead of the fake green card.
If you have any questions let me know, I learned of all this from one of my neighbors back on 02-03, he was from Guatemala, been here illegally laying low working regular job, drives a not too new not too old honda used to rent an apt, all with these documents. I moved but last I heard of him he still in the country, the only pain would be renewing your license but if you I wanted to disappear or you were wanted for something that will put you in jail for life it would be worth it.
The hardest part would be to cut ties with friends and family, I watched that show on discovery called "I almost got away" most of the time these mfrs are caught because they tried contacting a friend or family member.
Now all that won't work as well if you are already in the system, fingerprints will get you, but even then they have to find you first.