The following forum is explanatory and brief.Anyways I want to add on that for degistering for VAT,I have gone ahead and accessed my agent login with HMRC to do this following, I have clicked on 'deregister for VAT' and got this following message on my screen that:
"Your client has signed up for Making Tax Digital for VAT so you cannot submit their returns using VAT online services".
However, in order to submit the VAT returns for your client under Making Tax Digital you'll require the following:
1.An agent services account - this is different to your HMRC online services for agents account.
2. Secondly,the software that's compatible with Making Tax Digital for VAT that can link to your client's digital records
request to check the step by step for the guidance.
Then go ahead and sign in by using your agent services account if you want to: national debtline