Travel Mask Mandate Repeal Act of 2021 This bill prohibits federal agencies from mandating the use of masks or face coverings on planes, trains, buses, and other public conveyances and at transportation hubs to prevent the transmission of COVID-19. Specifically, the bill nullifies (1) the rule issued by the Centers for Disease Control and Prevention (CDC) on January 29, 2021, that mandates such use of masks or face coverings; and (2) orders and directives of the Transportation Security Administration that relate to the CDC rule.