There are two ways to get discharged in North Korea. One is to complete military service and receive a discharge order. Another is to be disgraced by self-harm.

In October 1990 I was discharged. A decade of long hard work has finally come to an end. (Omitted) I went to the District Administrative Committee and filed a discharge report. In North Korea, a declaration of discharge allows the district administrative committee to find a place to work. (Zhao Ying-ho, Carrots thief)
Some of her friends were reluctant to live in the army, shooting their feet and cutting their fingers. It is possible to get discharged, but Songbun gets worse with disgrace, and the path to success is closed.
There were about 6 of those 2500 regiments. (Asahi Newspaper Aera editorial department “exiles from North Korea”)

What kind of treatment will North Korea receive after being discharged? After discharge, some seem to have promised to enter the university they wanted. For example, the following conversation.

“How old are you now?”
After drinking so much, the instructor’s tongue was not tangled at all.
“I’m 16.”
“16? My nephew is older than you. Why did you come to the army so early?”
“I didn’t go to kindergarten and entered school.”
I didn’t want to explain it for a long time.
“Yeah, if you’re 16 you’re going to have to work for another 14 years, but you have the abilities. I want to say I’m a good soldier, but in a few years I’ll join the Labor Party and get out. Which college do you want to enter? Kim Il Sung University or Kumsong Political University?
An uneducated person like me dies, protecting the demilitarized zone to the end. And those who succeed will survive.”
(Ju Seong Il “North Korean People’s Army: Barracks in Living Hell”)

It is said that there is priority employment in the security department (secret police) and security department (police) after completing military service, in addition to entering university.

Many soldiers in the demilitarized zone are arrested for suspecting their homeland. On the other hand, soldiers who return to their home after successfully completing military service are awaiting priority employment in the security and security departments.
At the forefront of the class, communists who face the enemy in front of them want to guard the revolutionary leaders in the general public. It is a proof of true communism that has not been tempted by Korea and capitalism in the demilitarized zone for thirteen years. (Ibid.)

According to the following testimony, many people do not actually go the path they want.

There are two wishes for the NCO. To get rid of early, go home, get married, and have sex with a woman. However, the NCO’s wish is also a dream. After serving in the army for thirteen years, he cannot return home. The party also sends out evacuation soldiers in groups such as rural areas and coal mines.
This happened while I was the warehouse manager. Kim Jong Il ordered all troops who had been in service for 13 years to be grouped at Pyongyang Textile Factory. Even though you have completed your military service, your life will end if you do not follow this order.
Here’s the beginning of things. In the first place, the North Korean population has more women, so many women cannot marry. Conversely, all men have joined the army and, after completing 13 years of service, are over 30 years old. Women do not want to be married to a man of such age. Soldiers who join the party look for young women without seeing older women. Because it was like this, it was not easy to get together
The situation was the same at Pyongyang Textile Factory. There were many women who gave up marriage from the beginning, including unmarried women who were 60 years old. The manager of the Pyongyang Textile Factory was a well-known hero of the Korean War in North Korea. He wrote a petition to Supreme Commander Kim Jong Il, worried that too many men and women would not marry.
He seems to have broken the bamboo commander, Kim Jong Il. Without thinking about the result, he immediately issued a selfish command. They say that the soldiers will be married to women at the Pyongyang Textile Factory. Giving a home as a benefit. That was the very nuisance. Isn’t this the same as leaving a parent who is crying and waiting for this return in his hometown, and working as a second army until he dies? What are the feelings of the discharge soldiers? Some would have dreamed of a sweet marriage to a woman she met while working for the military. However, while in the army, romance was inevitable. Even if you leave your lover, you must still marry the person whom the Supreme Commander has decided. That is North Korean society.
After the soldiers were assigned to repair work and drivers at the textile factory, matchmaking began. The matchmaking is an arrangement in which one of the halls has discharged soldiers in one hall and women in another hall, and marries the first person she leaves. You are not allowed to look at the photos in advance. I don’t know anything about the other person. If you wait in line, your turn will come. So the first woman was a spouse. (Ibid.)

If their discharge is delayed in search of a promotion, they must accept low treatment.

Even if you have the money and power during your officer days, if you take off your military uniform, you will be a beggar. There is a saying in the North Korean army: “If you cannot sit in the back seat of your car, take off your military uniform as soon as possible.”
It means that you don’t regret being too late for taking off your military uniform, because you are inadvertently seeking promotion. However, there is nowhere to simply obey orders and accept middle-aged men who only know the military. At the time of discharge, he is given the position of a factory material manager or a company warehouse manager. But in factories where they sold out machines to buy food and workers retired and emptied to do their own business, their treatment is inferior to guards. (Ibid.)