To remove the lock from a Sony G8341 device, you'll need to use a tool like Sony's official Flash Tool, also known as Xperia Flash Tool (XFT). An FTF file is required for the process.
Here's a general report on the process:
This report is for educational purposes only. We do not encourage or support any actions that may void your device's warranty or potentially harm it. Always use official tools and files, and follow proper guides to avoid any issues.