Steve Ballmer steps down from Microsoft board of directors

Steve Ballmer, the new owner of the Los Angeles Clippers, was on form at the Staples Centre rally (AP)

Former Microsoft chief executive Steve Ballmer has step down from the company's board of directors to focus on the LA Clippers franchise he recently bought for a record $2 billion and continue teaching.

In a letter addressed to his successor, Satya Nadella, the 58-year old described Microsoft as "my life's work" and praised its software and innovation, but insisted "it would be impractical" to keep his seat on the board given his new commitments.

"In the six months since leaving, I have become very busy. I see a combination of the Clippers, civic contribution, teaching and study taking a lot of time", he wrote in a letter posted on Microsoft's website.

"Given my confidence and the multitude of new commitments I am taking on now, I think it would be impractical for me to continue to serve on the board, and it is best for me to move off."

Ballmer also signalled he would hold his shares in the company, of which he remains the largest individual shareholder, "for the foreseeable future". The Michigan native left his CEO role at Microsoft in February as the world’s 34th richest man, with an estimated fortune of approximately $20bn.

In a separate letter responding to the announcement, Nadella added: "As you embark on your new journey, I am sure that you will bring the same boldness, passion and impact to your new endeavors that you brought to Microsoft, and we wish you incredible success. I also look forward to partnering with you as a shareholder."

Earlier this week, an energetic, fist-pumping Ballmer treated Clippers fans to a pep rally urging the team to "go hardcore" ahead of the new basketball season as the franchise puts behind the embarrassing Donald Sterling saga.

"Something knocks us down and we’re going to get back and keep coming and coming and coming and coming... Hardcore, baby! Nothing gets in our way. Boom! Keep coming. Hardcore. The hardcore Clippers, that’s us," Ballmer told fans at the Staples Center on Monday.