Once Mac boots up, you can easily empty Trash. Now, you will receive a dialog box indicating thay the ‘System Integrity Protection’ is successfully disabled, to complete the process, you need to restart Mac.Here, you need to enter command: csrutil disable reboot and hit ‘Enter’.In the next window – listing all macOS utilities, select Terminal.Enter recovery mode on your Mac by pressing Command + R keys as soon as you start/reboot Mac.To turn off System Integrity Protection on Mac OS El Capitan or later, follow the below steps:

Disabling SIP for a while may help fix the Trash issues. SIP would even block you from deleted files / emptying files from the Trash. Mac with its latest release Mac 10.11, has got new feature – System Integrity Protection (SIP), in order to protect files from being modified by some malicious software. Once, done you can easily empty the Trash bin on Mac. To start Mac in Safe Mode hold Shift Key as soon as you start Mac and release it once Apple Logo appears. Hence, you will have to start Mac in safe mode, which doesn’t use much of your hardware resources or any login items. Your Mac might load some start-up items or use some files during start-up, thus it shows files in use when you try to empty Trash.

Once you restart or reboot your Mac, all these apps would be terminated. Some of the applications would be running in the background that uses files from Trash. In such cases, first, close all open files and folders. Also, some background applications might block you from emptying Trash. Sometimes, some of the files in Trash might be in use by some applications. When Files are in Use – Close all Files and Background apps If files are more, then this may take longer. This will add path of all files to the Terminal. Then just drag & drop all items to the Terminal, where you had typed the command. Now, open Trash from dock and select all files & folders in Trash. NOTE: Add a space after R or else this command will not work.

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