Microsoft Corp. Chief Executive Satya Nadella recently pledged to be "bold and ambitious" to remake the company and its culture. The first task, he signaled in a memo on Thursday, would be cleaning up some of his predecessors' messes.

The recently named Microsoft chief is cutting up to 18,000 jobs in the next year, or about 14% of the company's workforce, the largest layoffs in its history. About two-thirds of the cuts would come from its phone and tablet staff, which bulged after former CEO Steve Ballmer agreed...