How to delete the Time Machine's local snapshots

If you enable Time Machine on your Mac, you have the chance to recover your files even if the Backup Volume is not at the moment available thanks to the Local Backups: About Time Machine local snapshots - Apple Support

Despite the snapshots olden than 24 Hours are going to be automatically deleted by the operating system, sometime can be necessary to make in short time more space and for this reason you can delete the local snapshots with the following methods:

- Open the Terminal and give the following command:

sudo tmutil listlocalsnapshots /

- Following the previous command, macOS will ask you for your password:

Note that you won't have any visual feedback while typing your password.

- Press Enter and you will get the list of the local snapshots:

- At this point you can delete a snapshot with the following command:

tmutil deletelocalsnapshots 2018-03-03-193951

Of course in your case, change the "2018-03-03-193951" with the date it appears in your list.

- When done (is a question of milliseconds!), you will get a message like this one:

Deleted local snapshot '2018-03-04-085316'