The Metamorphosis Chapter 1

There are many ways that Gregor might've felt dehumanized. One way is that his parents had been using him to repay their debt, something that was not his responsibility, he is of course a grown man. Another way is that since he was always so punctual he was probably thought of as someone who was more like a clock than a human being. And althought he hated his job he always worked at his best which is quite odd.
His family also probably thought of him as a pest seeming as he was never to move out of his parents house and gain some sort of independence. His parents would always be stuck with him until they died unless they did something, but of course they didn't seem to care for him much since they did nothing. Another way that he might've felt dehumanized is that his bosses never really cared for him, just his productivity and his punctuality.