To change the premium payment mode of your policy, the simple thing to do is to write a letter to the LIC branch manager from where you have got your LIC policy. This is how it usually works but currently, it is not possible for you to change the premium payment mode online.
What you should do?
You can either post a letter with your identity proof addressing to the branch manager or you can submit the documents to the branch in person.
For you to better understand a sample template has been attached below.