Windows 8 comes with its own antivirus protection called Windows Defender. To see if it is switched on go to Control Panel, then Action Center, Security and click on the down arrow then check under Virus Protection that it says "Windows Defender is helping to protect your PC"
Don't know why anyone on this forum would have advised you to remove CCleaner as it is one of the most valuable utilities to have for maximising disk space. However it does not remove Malware.
One of the most popular programmes for removing malware is Malwarebytes and you can find that with a simple Google search, it is perfectly compatible with Windows 8.
You can still access all the Windows tools for disk clean up and defrag in Windows 8 just as you did in earlier versions of Windows. Go to the desktop and double click on MyPC or ThisPC in 8.1 then when you see your hard drives listed right click and scroll down to Properties. Click on the Tools tab and then on Optimize.