Ever since one of the latest updates CCleaner is always on when I start Windows. I always toggle "Launch the CCleaner app window each time the computer starts" off, and while the window of the app does not in fact open, the program is still to be found in the hidden icons section of my taskbar.
I do not want the program to be open when I did not specifically open it, so what do I do?
What you are seeing is not "Launch the CCleaner app window each time the computer starts" setting.
That launches CCleaner to do a clean and then closes.
What you are seeing is an Icon in the System Tray area of the taskbar (in your case in the hidden part accessed by the up-arrow) which is put there by Windows when CCleaner is running a background task.
There are two CCleaner background tasks that can cause Windows to show that icon:
Smart Cleaning.
"Keep CCleaner updated automatically" setting.
As you say this is only happening for you since a recent update then it is most likely the new "Keep CCleaner updates automatically" setting, which was introduced in CCleaner version 5.47 for both Free and Pro users.
If you don't want the automatic updating then go to Options>Updates and untick it.
Windows should then remove the CCleaner icon from your System Tray (hidden area).
If the icon is still there after unticking the automatic updates then that will be because you also have Smart Cleaning enabled.
Again you can untick 'Enable Smart Cleaning' to turn that off.
If you have either one (or both) of those two options selected then Windows will put the icon in your System Tray.
We have seen this persistence a couple of times before, it seems to be due to the order in which the updates/settings were done, (or possibly some Windows Task setting on those particular machines?)
Anyway, following the 5 steps given in this linked post cured it for those others: