Once you are into your cPanel you will see the 'Spam Assassin' icon in the mail section.
Once into the 'Spam Assassin Settings' you can enable it by clicking on the top button:
To setup 'Auto Deletion' of your spam select a setting - 5 is default - higher is conservative while the lower score is harsh - but remember if you are too low it may delete friendly emails so start with 5 and adjust to suit, then click the middle button 'Auto Delete Spam'.
You can further refine your settings by adjusting the 'Configuration settings' (Bottom button) and lowering the 'Required_Score' from the default 5 - saving before you exit.
Other ways to minimise spam is to set up 'Account Level Filters' and follow the prompts there - see here for more details.
