I am running the following command to update my TypeScript version from 1.8.5 to 2.0.7 :
npm install -g typescript
it shows as -
Down load "TypeScript_Dev12.exe" and run it.
After successfully installing, you will find "C:\Program Files (x86)\Microsoft SDKs\TypeScript\2.0" in your system. Copy that path.
Now go to Environment Variables->System Variables->Path, now click on edit. Remove old path of type script and add new path over there.
Now restart your system. You will now find 2.0 as your typescript version.
Megha shah is right, but I think is better to install via npm globally
npm install typescript -g
and so use the existing C:\Users{username}\AppData\Roaming\npm.