You can tear off DaisyDisk’s petals and drop them to the special area called “Collector”:
In addition to drag-and-drop, you can put files and folders to the Collector by selecting the Move “Selected File” to Collector command from the item’s context menu, or by pressing ⌘⌫ hotkey while pointing to an object.
Don’t worry, the files remain intact until you click the Delete button.
You can expand the Collector by clicking on it to make sure you are not about to accidentally delete some needed files. The expanded Collector works just like the sidebar, so you can preview files and drag them out. Another way to get an item out of the Collector is to point and click the × button near its name
Some folders like
/Library or current user’s home folder are not meant to be deleted, so the Collector will not accept them. Semi-transparent (consolidated) petals also cannot be removed, you’ll have to expand the group and drag individual files and folders.
Clicking the Delete button starts deletion process, but you’ll have 5 seconds to change your mind and press Cancel.
DaisyDisk permanently removes files and folders instead of moving them to the system Trash, so that the disk space is actually recovered. These files cannot be “undeleted”.