1. Click on the 'pencil' icon to take you to the 'Edit Course List' screen:
2. Click on the 'hide link' button which is adjacent to the section you wish to hide:
3. Return to your main 'My WebCT' screen by clicking on the 'My WebCT' tab at top left:
That's it! Hidden.
Oh - and you can also hide a number of sections at once by selecting the appropriate sections and then clicking the 'hide' box at the bottom of the 'Edit Course List' screen: