"The new chief executive is expected to start later this year, and with the shares at a six-year low, steadying the ship will be their first task", said Khalaf.
Jan du Plessis, former chairman of mining group Rio Tinto who took the same role at BT last November, said the board supported Patterson's strategy but it did not have confidence in his ability to see it through.
"The broader reaction to our recent results announcement has. demonstrated to Gavin and me that there is a need for a change of leadership to deliver this strategy", he said.
Mr Patterson has been seeking to reboot BT since a profit warning early previous year, and told investors last month that it will take until 2021 for a return to profit growth as the company reorganises.
It snapped up mobile operator EE for £12.5bn back in January 2016, while BT has spent billions of pounds acquiring various sports rights for its BT Sport TV channel which launched around the same Patterson joined.
"At least one thing that the new CEO will have on their side is the shares' rotten performance under Mr Patterson".
Patterson was also embroiled in fractious talks with Britain's telecoms regulator Ofcom about the fate of Openreach, which runs the national broadband network.More news: Yahoo Messenger to Shut Down on July 17
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The company has been reeling from an accounting scandal in Italy previous year and has spent billions on buying football rights to attract customers to its pay-TV channels.
Gavin Patterson, CEO of BT, speaks at the Conferederation of British Industry's annual conference in London, Britain, November 6, 2017.
The subsequent revelation that BT paid Patterson £2.3m a year ago generated further negative PR, and at the start of June, it emerged that some BT shareholders were actively mobilising against him.
Mr Patterson said: "It's been an honour to lead BT since 2013 and serve as a member of the board for the last 10 years".
He added: "But with his troubled reign over and the restructuring dirty work announced, investors can look to the future".
BT shares rose more than 2% in early trading.