How to delete a system app? How can I delete any system app? I deleted a wallpaper app in my app folder but I don't see any changes? I want to delete some apps especially default factory-installed apps. Is there a simple way?
Root:
You can install Titanium Backup to uninstall unwanted apps easily.

Without Root:
I found an interesting article which helps you creating a script to remove certain stock APK files.
Check it out here.


Download the recovery flashable BloatKill script in zip. Do not
extract it: bloatkill.zip.
Download and install a zip manager program on your computer, such as
WinRAR or PowerArchiver.
Double click the bloatkill.zip to open the zip
Now browse over to META-INF\com\google\android\
Right click the updater-script file and extract the file to
desktop. You can also extract this file by dragging it to the
desktop.
Open the file with a suitable program like NotePad++, or Adobe
Dreamweaver. The opened script file should look like this:




ui_print("Unwanted stock apps remover.");

ui_print(" ");
ui_print("Partitions mount");
#Properly unmounting to avoid issues
run_program("/sbin/busybox", "umount", "/system");
run_program("/sbin/busybox", "umount", "/cache");
run_program("/sbin/busybox", "umount", "/data");
#Then mounting
run_program("/sbin/busybox", "mount", "/system");
run_program("/sbin/busybox", "mount", "/cache");
run_program("/sbin/busybox", "mount", "/data");

ui_print(" ");
ui_print("Unwanted stock apps remover");
delete("/system/app/StockApp.apk");

ui_print(" ");
ui_print("Unmounting partitions");
run_program("/sbin/busybox", "umount", "/system");
run_program("/sbin/busybox", "umount", "/cache");
run_program("/sbin/busybox", "umount", "/data");

ui_print(" ");
ui_print("Finish");



The line delete("/system/app/StockApp.apk"); being the app you want to delete.


When the editing is over, save the changes and exit NotePad++ or the
    editor you are using.
Now drag the updater-script file back to its place:
META-INF\com\google\android\ folder in bloatkill.zip
Now copy the bloatkill.zip file to the root/main directory of your
phone’s SD card (/sdcard/)
Open phone Settings and enable USB Debugging Mode from Developer
 Options.
Turn off your device and boot it into Recovery Mode. The method
 involves a special combination of hardware keys that are pressed
 simultaneously and differ from device to device.
In the recovery mode use the volume keys to scroll/highlight and
 the power key to select an option.
Scroll to an option called apply zip from sd card and select the
 bloatkill.zip file.
Confirm your choice by selecting yes.
Finally, select reboot system now.