Tesla is ending production of the Model S and Model X and will convert its Fremont, California, plant into a production facility for the humanoid robot Optimus.

On Jan. 28 local time, CNBC reported that Tesla CEO Elon Musk said on a fourth-quarter earnings conference call that he will end the Model S and Model X programs. Musk said it was time to conclude the two models with honor and that customers considering a purchase should order now.

The Model S and Model X are Tesla's oldest vehicles, and the company has continued cutting prices in recent years as competition in the electric vehicle market has intensified. The Model 3 and Model Y, by contrast, are Tesla's core models and accounted for 97 percent of last year's total deliveries of 1.59 million vehicles.

The decision comes as Tesla's performance slows. In this earnings release, Tesla posted its first annual revenue decline since its founding, and revenue fell in 3 of the past 4 quarters. Musk is shifting the company's direction away from its traditional electric vehicle business and toward future businesses such as self-driving cars and humanoid robots.

Tesla plans to remove the Model S and Model X production lines at the Fremont plant and replace them with an Optimus line with annual capacity of 1 million units. The company is developing Optimus, a bipedal intelligent robot capable of carrying out a range of roles from factory work, and plans to unveil a third-generation model this quarter with mass production in mind.