To install PITAKA MagEZCase is fairly easy because it's extremely slim. You can refer to the installation and uninstallation instructions in the package. You can also get the instructions from these videos:
for iPhone: https://www.youtube.com/watch?v=uKA9ICc0t4w
for Samsung phone: https://www.youtube.com/watch?v=EerqaZ0KGFQ