I am creating an app with “Ionic nameApp sidemenu start”, then I go into the directory created, and while I adding a platform, the terminal tells me that platform already added …

@RTeran you can check in your project folder if the platform folder contains any folder (android or ios)
> cd platorms
>ls
You might have android already installed!
iMacBook-Pro-de-RTeran:pruebados rteran$ cd platform
-bash: cd: platform: No such file or directory