Q: secure delete files

No.  Just.....no.  CleanMyMac and all of its ilk are garbage and nothing but trouble.  They're scams, and people who install them on their hard drives are asking for a lot of problems they don't need and didn't ask for.  All you have to do is search these forums for "CleanMyMac" or "MacKeeper" and you'll see what I mean.

I just don't like that it encrypts everything and forces you to log in anytime you shut down, restart, or sleep.  Just overkill for me.  The disk utility is much more selective which works perfectly for me.  Heck, I can pick a single folder and put everything that I need secured in it and, bang, I've got a clean solution!

If you're aware of the caveats that secure delete from the terminal can potentially damage your SSD and that secure delete has the potential to delete files necessary to the OS to function, and the potential to erase your entire dive with a keystroke that is your decision to use it, but I do not think it's wise to promote it to others as a viable solution when Apple Computer took this functionality out of El Capitans GUI for good a reason.