Hi Suraj,
No you cannot change the required fields of standard objects but you can do that in the custom fields of Custom objects.
There are certain standard fields on some standard objects that you will always have to use if you want to use the object. As it happens all objects need to have a name field.
The name field of an object is a required field that has a special place in the life of the object. The record name is intended as a human-readable identifier for a record. It’s not required to be a unique identifier, but it is supposed to be the primary way users distinguish one record from another. In the automatically generated user interfaces, you’ll see that the value for the name is always displayed as a link to the record itself, to its own detail page.
Hope this may help you:
Thanks