The NBA does not require players to have a high school education. However, rules require players to be at least 19 years of age during the calendar year of the draft. One full NBA season must have elapsed since their graduation, as well; if they did not graduate from high school, then they still must wait until one NBA season has elapsed since the graduation of the high school class the player would have graduated in had he finished high school.
For automatic eligibility into the NBA draft, players must have completed four years of their college eligibility. This does not mean a college education is required, however. If a player chooses not to go to college, they must wait until four years have passed from their graduation from high school. Also, if a player signs a contract to play basketball outside of the NBA, they must first be released from that contract before going to play for the NBA.