He gave up in disgust when his boss began to treat him in too handed a fashion. What is the meaning of this line?

Hello,

The text in reference means that his boss became unbearably authoritarian and was very difficult to tolerate.Patol Babu couldn't bear the oevrbearing or arbitrary in which he was treated by his boss.

The oppression was too much for him to take. Thus, he left that job in disgust and repugnance.