LONDON—HSBC Holdings PLC said it would shed 35,000 jobs and cut business lines and customer relationships across the U.S. and Europe, the latest phase in a decade long retreat from global ambitions to focus on its Asian heartland.

The planned overhaul of the U.K.-based bank, one of the world’s largest by assets, marks a significant step in a reorganization that started in the wake of the global financial crisis. Founded in Hong Kong in 1865, HSBC operates in 64 countries and territories but makes half of its revenue in Asia.

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