Freeing up space · Free Up Space wizard and button
Can I back out of the Free Up Space wizard without anything changing?
Short answer: Yes. Only each step's confirm button writes to your disk, so you can open the wizard, look around, untick items and cancel with no side effects.
Yes. In the wizard, each step's confirm button is the only thing that writes to your disk. Opening it, browsing the checklists and unticking items change nothing, and you can cancel at any point before confirming with no side effects.
The same holds for Emergency Space: pressing Free up space there opens a review headed "Nothing has happened yet" — see what that review shows.
Once a clear-up is running you can still stop it safely; see can I stop a clear-up halfway.