If your turnover falls below £83,000 or you have ceased trading, you can cancel your VAT registration by logging on to your VAT online account (i.e. your Government Gateway account).
If you prefer, you can deregister by post by submitting a VAT7 form to the address stated.
HMRC requires that you prepare a 'final return'. This final return needs to include declaring VAT on the market value of the assets that are being kept in the business if either of the two conditions apply:
- You could reclaim VAT when you bought them;
- The total VAT due on these assets is over £1,000.
It's always best to wait until your financial statements are completed - your accountant may provide adjustments needed, and these can be included in the final return.
You can find the links to deregister online or by post on this .gov webpage.