My German permanent residence permit (Niederlassungserlaubnis) is in printing process since officer said it takes 4 -5 weeks.
Now I want to change my job, is there any chance my current employer can ask visa officer to deny my PR ?
Your permanent residence was granted on the day you were at the "Amt". You should have a paper saying it was granted. This paper should serve as your temporary permanent residency permit until your real one (looks like a German ID, so it's a plastic card with your picture on it and cannot just be printed out with a regular printer at the Amt) is printed.
Your permit was granted. The printing is a formality that nothing can change. Your papers should say so.
Please don't rely on people on the internet. Look at what your papers say. This is a matter of great importance. Do you really need a new job so badly that you would risk your residency over what a stranger said on the internet? You waited 5 years for this, just wait another 4 weeks to be sure.