Clear reading list

"how do you right click with the pad?" - I don't have a trackpad. However, I believe that if you hold Control, while you click on the pad, you get the same context menu as a right click.

You can also do it this way:

1. Open System Preferences.
2. Click on the Trackpad icon.
3. Select the Point and Click tab.
4. Choose the checkbox next to Secondary click.

Once activated, you'll be able to right-click by tapping the trackpad with two fingers simultaneously.

Right-click on a reading list item and then click on "Remove item".

If you want to clear all entries, en-mass, open the Safari sidebar, and then the Reading list there. Then, right-click on one of the reading list items there and you will see the option to "Clear All Items..."