How do I update golang from command prompt on Windows?

I think that GVM could be a good option for that. GVM is an interface to manage Go versions in your computer. It allows you to change the Go version and even installing/uninstalling different golang versions by command prompt.

You can install a new version by typing:

gvm install go1.4 -B
gvm use go1.4
export GOROOT_BOOTSTRAP=$GOROOT
gvm install go1.5

Or even get a list of golang versions installed in your computer:

gvm list

More information can be found on their website: https://github.com/moovweb/gvm

Go can also be updated using the Chocolatey package manager. Run from an elevated shell to minimize the risk of installation issues.

Install using:

choco install golang -y

Update using:

choco upgrade golang -y