File Uses
When you select a file or folder in OmniDiskSweeper, you can see what parts of your computer system are using it so that you don't accidentally delete something that is necessary for your computer. At the bottom of the browser window you can see the file title, size, and what packages it is part of. You should first focus on files that are not part of packages. These files are listed in the browser window in black. However, just because it is not part of a package does not mean that it is not important. OmniDiskSweeper only knows about the packages installed from an Apple installer, which means that if you have installed a non-Apple application the files in that package will not be marked as being part of a package. Keeping this in mind, please make sure you really don't need the file before you delete it from your computer forever.