Resign with few days notice

I am working in a private organization for almost two decades. Presently I am a senior software developer here. Since a year, I am facing harassment and humiliation in various forms. My earlier reporting person resigned in 2020. Last year several of my tasks (which I have been doing since 15 years) were taken away by a senior person of a department (I have to deal with this department's statutory software applications) and was given to a person in his department, without any discussion with me. Later, HR called me and complained that I don't have much work so company may not keep such employees, etc. In the room there was another person and the HR head. I immediately objected and talked about all my responsibilities. I also provided a detailed printout of my tasks. They didn't believe much and I faced many humiliating and derogatory comments from both. Also, this humiliating person was told to be my new reporting person. Basically the objective seems to be to remove me and distribute my tasks to two persons to save them. The entire atmosphere is very venomous and suffocating for me. I am filled with agony and anguish since last year. I have decided to quit. My appointment letter has this clause - "Your services will be terminable by one month's notice from either side without assigning any reason. Your services may however, be terminated by the company with payment of an amount equivalent to one month's pay in lieu of one month's notice." I want to know (a) what steps can be taken against me if I resign with very few days notice? (b) What should be my ideal steps to take at this gruesome hour?