You can get JEE Main Mathematics syllabus from the link below
For JEE Main, you have to study partial fraction. There may not be any direct question from partial fraction but there will be questions where you have to use the concept of partial fraction. As an example, Integration is an important chapter in JEE Main and to solve some type of integration problems you have to use partial fraction. So, its better to grasp the basics of partial fraction. Don't totally ignore it.
Check the link to know about important chapters in JEE Main
The syllabus of jee has been cut down as per the education minister. But till now, no new syllabus structure is released.
So, the partial fractions, is in jee mains syllabus.
And this concept is widely used in solving integration.
So, many complex integration can be solved by partial fractions.
Also check out the following link to know the syllabus of jee mains :-