Can I quit my job and become a day trader?

First of all, you must have a sizable capital(which I presume you already have invested in portfolio of stocks), of which a good amount is sitting liquid as cash.

Furthermore you must be invested into good news platforms in order to take a postition quickly based off latest market news to ride swings and momentums. That is how I would do things if I were a swing trader.

Like what Jonathan said- at the end of the day, it boils down to whether you are confident you can consistently generate returns from your investment strategy.

How confident are you of your system that it will succeed? You may want to do a trial run first before plunging into it full time. Ideally your profits should minimally cover your monthly expenses consistently before you fire your boss.