First of all, please make sure you have Brew installed on your mac. Follow this tutorial if you need to install brew.
Open your terminal then run the following command
brew install go
Installing Brew on Mac
Brew is a powerful package manager for Mac. If you are familiar with apt on Ubuntu or Yum on Centos, brew is the same kind tools for Mac.
Open Terminal then run following command
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew doctor
brew update
brew upgrade