I'm new for ethereum. I downloaded the wallet. I found out I'm on test net. I moved to main now. I would like to delete blockchain file of test-net if it is different then main? Thanks
Yes, the mainnet data will be different from the testnet and you will have to redownload the data. If you are using mist, then you can find the data directory at
~/Library/Ethereum on mac.
Your data is stored in chaindata folder which is
~/Library/Ethereum/chaindata. So you can delete this to remove the data.