Thanks for the question. The following resource outlines the process of deleting locked files:
Deleting locked files
Locked files can easily be deleted if you press Shift-Option or Option key combination while emptying the Trash (in Mac OS X 10.1 and later). For Mac OS X versions 10.0 to 10.0.4, use Show Info to deselect the item's Locked checkbox.
If you still cannot delete the item, start up your computer from the Mac OS X installation disc and choose Disk Utility from the Installer menu of the first screen. Use Disk Utility to verify and, if necessary, repair your disk.
If a file can't be unlocked, you may not have permission to unlock it. See this article to learn how to get write permissions.
If the issue persists, use Disk Utility's Repair Permissions feature to check your Mac OS X volume.