to unlock lock screen of mobile

Do you want to keep the data on the phone and remove the lock security or do you want to wipe the phone without keeping any data and remove the lock security?

Option 1 is harder to do while Option 2 is a lot easier to do.

Option 1:

Note: Best to follow the instructions posted in this link: http://forum.xda-developers.com/showthre...

1. Flash a custom recovery called ClockWorkMod / TWRP / Philz Touch Recovery.
2. Boot to recovery, mount the /system and /data partition
3. Use the Aroma File Manager (A flashable one via custom recovery)
4. Navigate to /data/system and delete the password.key file to remove the password, works on most android versions and probably not the latest ones such as lollipop and higher depending on security level.
5. Reboot phone once you have deleted the following file(s)
6. Lock screen security should be removed.

Option 2:

You will lose all data on the phone following the steps below:

1. Turn off the phone if you haven't already. Hold volume up + power button and home button.
2. Stop holding the power button + home button + volume up button when the Samsung logo appears and/or a blue text at the top left of the screen says booting to recovery.
3. Once it has booted to the Android recovery use the volume up and down keys to select / highlight a option.
4. Select the wipe data / factory reset option and use the power button to select this option.