How can the No Child Left Behind (NCLB) Act be overturned?

The NCLB Act is an act of Congress that was signed into law in 2001. There are only two ways for it to be overturned.
The first way is through a court challenge asserting that the law is unconstitutional. This is unlikely to succeed because it changes funding schemes for schools and encourages adherence to certain standards to obtain funding. Laws of this nature are generally difficult to challenge because Congress has broad discretion in how is apportions funding and because the harm is less clear, making it more difficult to assert standing.
The second method is through another act of Congress that either repeals or amends the NCLB. This occurred in 2015 when Congress passed the Every Student Succeeds Act (ESSA). The ESSA did not repeal NCLB, but it did shift the accountability provisions to the states to allow for greater flexibility.