1. By a subsequent constitutional amendment: An amendment can be repealed by another amendment that explicitly states that the previous amendment is repealed. This method of repeal has been used only once in U.S. history, when the Twenty-first Amendment repealed the Eighteenth Amendment (which had established nationwide prohibition of alcohol).
2. By a convention of the states: A convention of the states can be called for the purpose of proposing amendments to the Constitution. If two-thirds of the state legislatures call for a convention, it must be held. Any amendments proposed by the convention must then be ratified by three-fourths of the state legislatures or three-fourths of state conventions. This method of repeal has never been used in U.S. history.
In either case, the process of repealing an amendment is intentionally difficult and time-consuming, in order to prevent amendments from being repealed lightly or frequently.