In order to change the company's name after it is formed, an amendment to the Certificate of Formation/Incorporation needs to be requested to the registered agent. For further details on how to contact the agent, please find this support article.
On our side, we can easily update the Operating Agreement/Post Incorporation package for your company once the amendment is ready. Or if you prefer you can go ahead and modify the Operating Agreement/Post-Incorporation on your end to reflect the updated name.
If you either have the EIN letter or it is already in progress, you will need to notify the IRS about the company's name change by either sending a letter or during the annual tax filing. You can also try to contact the IRS by phone to request the change. Further information can be found on the IRS website.