My business is now incorporated with Companies House. If I have not started the business yet can I just fill out the DS01 and pay £10 to remove and close the company and start as a sole trader?

A limited company can request to be closed/dissolved under Section 1003 of the Companies Act 2006, providing that it meets all of the following requirements:

Not traded within the last three months
Not changed the company name within the last three months
Is not subject to any legal proceedings, current or proposed
Has not made a disposal for value of property or rights.

When all of the above criteria are met the Striking Off application (DSO1) can be completed. Form DS01 Striking Off application must be:

Signed by the majority of directors
Submitted with a £10 fee to:

Companies House, Crown Way, Cardiff CF14 3UZ, for English and Welsh companies

Companies House 4th Floor Edinburgh Quay 2, 139 Fountainbridge, Edinburgh EH3 9FF, for Scottish companies

Companies House 2nd Floor The Linenhall, 32-38 Linenhall Street, Belfast BT2 8BG, for Northern Ireland companies.

A copy must also be sent to interested parties within one week of the application, eg HM Revenue & Customs, creditors, employees, members etc.

There is further guidance on the Companies House website here.

However, before filling in the DS01 and sending it off, I suggest you check whether this is in your best interest. It is unusual to get a company incorporated and then have it immediately struck off. Why did you incorporate in the first place? What has changed that you now wish to trade as a sole trader? Incorporation can offer taxation savings and many start-ups opt for that business format.

See also: Sole trader or limited company?