Delete files and folders
At any time, you can get rid of files, folders, and other items that you no longer need. You start by dragging items to the Trash, but the items aren’t deleted until you empty the Trash.
Note: If you turned off Time Machine or haven’t backed up your files recently, you may want to store a backup copy on a storage device, just in case you change your mind and want the item later.
Delete an item from your Mac or iCloud Drive
Drag the item to the Trash, or select the item, then press Command-Delete. If an item is locked, click Continue to confirm you want to move the locked item to the Trash.
If an item is locked, you need to confirm you want to move it to the Trash, or unlock the item before putting it in the Trash. To unlock the item first, select it, choose File > Get Info (or press Command-I), then deselect the Locked checkbox. If you are not logged in as an administrator, you may need to click the lock icon 
, then enter an administrator name and password.
Empty an item from the Trash
Control-click the item you want to delete, then choose Delete Immediately.
In the warning message that appears, click Delete.
Empty all of the Trash
Click the Trash, then click the Empty button in the upper-right corner of the Finder window. You can also choose Finder > Empty Trash.
In the warning message that appears, click Empty Trash.
Prevent the Trash warning message from appearing
Once: Press the Option key when you click Empty or choose Empty Trash.
Always: Turn off the warning in the Advanced pane of Finder preferences. Choose Finder > Preferences, click Advanced, then deselect “Show warning before emptying the Trash.”
If you change your mind before emptying the Trash
Click the Trash to open it, then drag the item out of the Trash, or select the item and choose File > Put Back.
Remove items from the Trash automatically after 30 days
Choose Finder > Preferences, click Advanced, then select “Remove items from the Trash after 30 days.”
Note: Items deleted from your Mac are permanently deleted. You may be able to recover items deleted from iCloud on iCloud.com.