I planned to change the package name through smali(reverse)
when I open up apktool.yml, I saw this
forced-package-id: \'127\'
To my knowledge there are no fast ways to change the package name.
You have to change the package="com.mycompany.myapp"
in Manifest.xml and then manually replace all the package name occurrences in smali files (and folders). Finally edit apktool.yml replacing the old package name, with your new package name.
A full detailed tutorial can be found here: http://forum.xda-developers.com/showthread.php?t=2760965