Root Required
Steps
1. Download Xposed Installer
2. Install it
3. Download IMEI pro apk
4. Install it
5. Open Xposed Installer
6. Go to sidebar (menu)
7. Click on Modules
8. Check IMEI apk Module
9. Reboot Your device
10. Open IMEI apk
11. Change IMEI
12. Reboot Your Device