This line is the chorus to the famous song Another Brick In The Wall part 2, part of Pink Floyd's 1979 classic The Wall. The entire album is the life story of a rockstar named Pink.
From the time he was a small child, a pattern of traumatic events in Pink's life have led him to build a figurative wall around himself as a shield from other people and the emotional scars they leave on him. Pink's father perishes in war, leaving him alone to be smothered by his overprotective Mother. His abusive school master takes pleasure in ridiculing and denigrating the school children, and in Pink's own words "exposing every weakness, however carefully hidden by the kids." (This is what leads to the childrens' sentiment "We don't need no education.") Later on in the album we learn that Pink's wife, tired of his absence on tour, is cheating on him, and his violent abusive nature even begins to drive away groupies. As Pink spirals deeper into depression, each of these events become "just another brick in the wall" that Pink is building around himself.
This metaphorical wall is the theme of the entire album. The first half of the album details some of the traumatic events that "built" the wall, culminating in Pink's attempted suicide, while the second half details the delusions that drug-addled Pink suffered inside his fortress of self-imposed isolation. In the album's denouement his conscience prevails and Pink puts himself on trial for all the harm that he's done to his loved ones.
The Verdict: TEAR DOWN THE WALL! TEAR DOWN THE WALL! TEAR DOWN THE WALL! TEAR DOWN THE WALL! TEAR DOWN THE WALL!