In all the notifications and information bulletin you will not find any way to change JEE Main 2020 Exam Center Allotment. NTA has also mentioned clearly that there is no provision for changing JEE Main exam center once it is allocated.
However, sometimes there is genuine situations in which is is not possible for the candidate to give exam on allotted exam center due to distance or any other reason.
In such situation, candidates can try their luck by using JEE Main 2020 Query Redressal System by NTA.
It is available in the JEE Main 2020 login. After login select “Request for Exam City Change after display of Admit Card” under Query type and explain your reason in the Query Description field.
You also need to attach supporting documents.
NTA will go through the queries and may accept your request to change the exam center.
After submission of the request, you can then check the status of their query and see if new center has been allocated to them or not.