Once the scan results are obtained, use the Daisy Disk graphics and the "heaviest" folder list (on the right) to locate the files that take up the most space on your computer. In the window that opens, click the button tomography placed next to the name of the drive where you want to free up space and wait for the scan to complete. When the download is complete, drag the software to the folder applications macOS and start it. To download Daisy Disk on your PC, you need to connect to their site Internet and click on the button Free Trial. It is up to the user to go to the folders identified by the software and get rid of the files that are too heavy. It is paid, it costs € 9,99, but there is also a free version available that has the only limitation of not automatically deleting files. It is a very simple to use application that analyzes all hard drives on the Mac and tells the user where the large files are located. If you are using a pre-Sierra version of macOS, or in any case want more granular control of "heavy" files on disk, give Daisy Disk a try. you can enable automatic emptying of the macOS tray every 30 days, while selecting the icon mail From the left sidebar you can remove the attachments from e-mail obsolete (and therefore probably useless) in one go.
I also point out that by clicking the button Activate. placed next to the article Optimize storagewhile for a generic description of the "bulkier" files on your Mac, click the button Review file.
If you want to delete iTunes content you have already seen, click the button Optimize. placed next to the article Store in iCloud (requires a paid iCloud plan). If you want to delete photos and videos from your PC by storing them in iCloud Drive, Click the button Optimize. and choose which cleaning function to use.
To use the disk cleanup tool included in macOS, click the apple located in the upper left, select the item Information about this Mac from the menu that opens and click on the tab archive present in the window that appears. with macOS 10.12 Sierra, Apple has included in its operating system a very useful tool that allows you to free up disk space by storing photos and videos in iCloud (requires a paid iCloud subscription), deleting already viewed items downloaded in iTunes, emptying the trash and identifying the files that take up the most disk space.
At this point, you have to wonder how to identify "useless" files on your Mac and the answer is included directly in macOS.