Every English sentence needs a subject, and a verb. The entire sentence depends on the subject and the verb. In this case, the subject is "I" and the verb is "am" (I'm is short for I am). When you say "I am" you are talking about something that is happening right now or present tense. So, it is necessary to say working, because that is happening right now.

Hello Anett, Without more context (situation) it is difficult to say but I think that it is a person who is not happy with their job and they are using the present continuous to talk about the future. "The boss was really mean to me today, I'm not working there anymore" Hope this helps Bob

Think about that situation, Someone ask to you, Are you still working in etc company. You can reply as " I'm not working there anymore" or "No, I dont work there anymore"

Ryan Kerby explained it corrctly. Although for reference a better way of saying this statement would be: "I do not work there anymore".

i still can't understand what do you want to ask