Can i change gross income mentioned in my form 16 while itr

You can't change the figure mentioned in your Form-16. The figure has been mentioned in the form-16 that means that figure has already been reported in your 26AS form. And you have to consider such figure what is being shown in the 26AS. You can show higher amount than the 26AS in your ITR, but if you are showing less amount than that, it is possible you will receive demand order from the department. 

So, according to me, you have to go with as per the Form-16 & 26AS figure, or,

the organisation, from which you are receiving salary, has to revise its TDS Return for the respective quarter where the mistake occurred to put your correct salary figure and accordingly the rectified figure will be reflected in your 26AS and Form-16.

Hope this will help you.

Thank You so much Sir for your clear clarification. I am highly obligued.