Peremptory challenge
Explanation:
Jurors aren't selected, they are not discarded, which is not exactly the same. Jurors are selected from a pool of registered voters, or registered, etc. (the selection pool varies in different states). The process of selecting possible juries is called voire dire, and attorneys have two ways for discarding jurors:
Challenged for cause and discharge: jurors can be discarded based on personal biases or conflicts of interest.
Peremptory challenge: attorney's representing each side may discharge a certain number of jurors without any specific reason at all.