In iOS it’s quite easy, you just delete the app and all of it’s data is removed as well. But how do you do it in OSX? Well, you should remove:
~/Library/Application Support/<YOUR OSX APP BUNDLE NAME>/
for example, by default should be:
~/Library/Application Support/com.yourcompany.yourapp/
And this is it! I suggest you do a Project -> Clean Build folder (to see this option you will have to press Alt while in the Porject menu) afterwards, just to be sure.
Questions / comments? I’m at @MarcMasVi
Marc