Paul's extreme attachment to his job has led him to, literally, lead a double life in his mind. While he does attend school and carries out with everything his father tells him to do, his mind is somewhere else. He creates fantasies that he cannot catch up with later. He immerses himself way too deeply into the arts, and the theater. Paul is entirely too invested in his fantasy.
We know that a consequence of this devotion to his job is that Paul takes leeway and comes home late. We know that he dreads returning late to Cordelia Street because he knows that one of the things that will await him is the sight of his father reproaching him his lateness
...his father, at the top of the stairs, his hairy legs sticking out from his nightshirt, his feet thrust into carpet slippers. He was so much later than usual that there would certainly be inquiries and reproaches.
This established, let's see what happens when Paul really gets in trouble. The first thing his father does is take away the Carnegie Hall job, which sets the inciting events that lead Paul to make the ultimate decision of theft, escaping, and then dying.
Paul was taken out of school and put to work. The manager at Carnegie Hall was told to get another usher in his stead; the doorkeeper at the theatre was warned not to admit him to the house; and Charley Edwards remorsefully promised the boy's father not to see him again.
Taking this away from Paul is, essentially, taking away his entire identity. He was alive when he was an usher. He was empowered, befriended, accompanied. Happy. To switch from the Carnegie into a firm to work as a clerk is the worse punishment. However, it is clear that the father saw that the theater was melting away the core of Paul's reality. As a realist, his father knew that it was time to cut the issue from its root. This is when all breaks loose, and Paul chooses to take matters into his own hands.