Change Excise Duty Group on the Material Master

What are the steps to change the excise duty group in the Material Master (MARC- OITAXGRP)? I am getting a message 'Excise duty tax group cannot be changed due to posted stock'.

We realised some of materials have been setup with incorrect excise duty group at a few plants and there have been a lot material movements posted (101s, 301s). But is the best way to fix this?

Do we have to reverse all the documents or is it good if we zero the inventory and then it will allow us to change?

Is a direct table update of the table an option?

Please advice.

Thanks in advance

Srini