WASHINGTON—The Commerce Department said Monday it was rescinding a list of prohibited transactions with TikTok and WeChat that were issued in September as the Trump administration sought to block new U.S. downloads of both Chinese-owned apps.The withdrawals came after President Joe Biden earlier this month withdrew a series of Trump-era executive orders that sought to ban new downloads of Tencent-owned WeChat and TikTok, and ordered a Commerce Department review of security concerns posed by those apps and others.The Commerce Department under Trump also had sought to ban other transactions that would have effectively banned WeChat’s use in the United States...