Sole trader change of business activity

I am a sole trader and have closed my existing business. I have now started a new business with a different business activity, How do I inform HMRC?

Hi Pauleyley,
You can inform HMRC in writing, addressed to:
H.M. Revenue and Customs
Self Assessment
BX9 1AS,
Or by telephoning our Self Assesment helpline:
Self Assessment: general enquiries
Thank you.