Begin by clicking the "Grades" tab and then clicking on "Manage Grades" at the top left of the page.

Next, click on the "More Actions" button at the top of the list and scroll down to "Delete."

Finally, click on the box to the left to the grade item you'd like to delete and click on the blue "Delete" button at the bottom of the page.

NOTE: if you are unable to delete a grade item it is likely connected to a discussion, quiz, or assignment and you need to unlink it first. To do so edit the discussion, quiz, or assignment and click on the "in the gradebook" dropdown

Next click on "Not in the Grade Book" or "Reset to Ungraded." Click Save and Close. You can now repeat the steps listed above to delete the grade item.