Simply move it to the trash folder, and when you click Empty Trash... or press Shift + Command (Apple) + delete, make sure you hold down the Option key.
Allows to unlock, delete, copy or rename a locked file; Can delete a file at next OS restart; Allows to kill locking process; Allows to remove locking ...
Type del filename and replace filename with the name of the locked file. After the locked files have been deleted, type exit on the command window to exit ...
Step-by-step: Download and install file lock software such as LockHunter or Unlocker. Launch the software and navigate to the locked file. The software will show which process is locking the file. You can then choose to unlock or delete it