Legal Question in Business Law in California

Sure can. They can also renege on an advertised price as long as it was not an intentional "bait and switch."

Most companies publish the intended ending date on special promotions, but unless the seller is deliberately (intentionally) misleading the public, it may discontinue a promotion without prior notice. If interested, you may want to look up California's main laws on unfair business practices, which are found at Business & Professions Code sections 17000-17051; 17200; 17500 (and sections following the listed section). However, these provisions would not ordinarily prevent an advertiser from terminating a special sale without notice.