Symantec products can be a little tricky when it comes to uninstalling. Thankfully, Symantec provide a dedicated uninstaller available from here

NOTE: The Norton Removal Tool uninstalls all Norton 2009/2008/2007/2006/2005/2004/2003 products, Norton 360 and Norton SystemWorks 12.0 from your computer

If you are not trying to keep program for later use then you don't need to log in, just go to Download and run the Norton Removal Tool step (usually step 3 or 4, depending on the program) and click on the download button, then run it.

As you seem to have already downloaded ccleaner, run it afterwards before installing the new antivirus program