Why aren't 500 1000 5000 and 10000 dollar bills printed anymore?

Printing of higher-denomination bills were discontinued in 1945, and distribution through banks was discontinued in 1969 by executive order of President Nixon in an effort to stop their use in criminal activities. The bills remain legal tender but any that are received by a bank must be turned back to the Treasury Department.

The primary reason was their use by organized crime, but they were also becoming less necessary because of electronic banking.