The site has switched to a memorial page with a dark brown background.
It reads simply: “In loving memory of His Royal Highness The Duke of Edinburgh 1921-2021
“Thank you for your service…You will be greatly missed.”
Harry is likely to travel from the US to attend his grandfather’s funeral.
The duke is living in California with the Duchess of Sussex and has not returned to the UK since stepping down as a senior royal just over a year ago.
Funeral arrangements for Philip, who died on Friday morning at the age of 99, have yet to be confirmed, but it is likely Harry will be among the small number of mourners, the PA news agency understands.
It is not known at this stage whether the Duchess of Sussex, who is pregnant with her second child – a daughter, will accompany him.
During England’s national lockdown, funerals can be attended by a maximum of 30 people.
It would be the first time Harry has joined the royal family since Megxit and also since his and Meghan’s bombshell interview with Oprah Winfrey in which they accused the royal family of racism and the institution failing to support a suicidal Meghan.
The two-hour interview was aired while Philip was in hospital after surgery on his heart.
The Queen issued a statement saying “while some recollections may vary”, the issues would be taken “very seriously”, but dealt with privately as a family.