Disk Wipe does not work on my free version.
Is that normal? Do you have to buy the pro version to get disk wipe to work?
No, you do not need pro to wipe; the free version is not hobbled in this way.
I assume by wipe you mean full wipe and not "wipe free space"; I also assume that you are looking at it toward wiping your c drive. This would be impossible as the windows in which ccleaner is living would be wiped by the process. Wipe full drive only works on secondary drives, and I think they must not have windows folders but that may have changed.