How to delete a file in your MAC?
Drag an item’s icon to the Trash (in the Dock), or select the item and press Command-Delete.
Choose Empty Trash from the Finder menu.
What if you can’t empty the Trash or move a file to the Trash?
In this case you might see a message like this: “The operation could not be completed because the item ‘(item name)’ is locked.”
Then try holding the Option key as you choose Empty Trash from the Finder menu.
Alternatively you can download a free app for this it is called Trash It!
Trash It! is an AppleScript-based application that force-empties your Trash and/or removes stubborn items. Especially useful if you have files or folders in the Trash with permissions set incorrectly, locked Trash items, want to securely delete a stuck item, or trash items from other partitions. If you drop files or folders onto the Trash It! icon, it will delete them as well. If you double-click on it, it will clean out your Trash can. This is the software recommended by Apple Tech support when all else fails!
Trash It! should be used when: You can’t get rid of trash.
Download the app here: http://www.nonamescriptware.com/