I have only just started using Angular 2 so it isn't a huge burden to go straight to version 4. If you have the CLI then Yakov Fain has a good and short set of instructions on removing the existing version and installing v.4. Which worked for me:
https://yakovfain.com/2017/02/05/upgrading-to-the-latest-angular-cli/
I'm not enough of a user to know if the '@' symbol is always needed but the following three command lines seem to do the trick
ng uninstall @angular/cli -g
ng cache clean
ng install @angular/cli -g
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