The U.S. Constitution does not explicitly grant Congress the authority to revoke the statehood of an existing state and revert it to territorial status. Article IV, Section 3 of the Constitution states that new states may be admitted into the Union, but it does not provide a mechanism for removing a state from the Union or reducing it to a territory. The Supreme Court case Texas v. White (1869) affirmed that states cannot unilaterally secede from the Union, and by implication, the federal government cannot unilaterally revoke statehood either.
Congress holds plenary authority over U.S. territories under the Territorial Clause (Article IV, Section 3, Clause 2), which grants Congress the power to "dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States". However, this power applies to territories, not to states that have already been admitted. Once a state is admitted, it enjoys full constitutional rights and equal footing with other states, and there is no constitutional provision allowing Congress to strip a state of its status.
While Congress has the power to admit new states and determine the conditions for statehood, including requiring a republican form of government and a constitution , there is no legal precedent or constitutional basis for reversing statehood. The process of statehood is considered irreversible under current constitutional interpretation. Therefore, Congress does not have the authority to revoke the statehood of a state like Minnesota and reduce it to territory status.