This question already has an answer here:

Once I create a smart contract and submit it to the blockchain, how can I go about updating it? I might want to do this because I have found a bug in the current version, I want to change some of the settings or simply release a new and improved version.

merged by eth Jun 23 '16 at 10:04

This question was merged with Upgradeable smart contracts because it is an exact duplicate of that question.