If the test that you have administered has not been started by any students in the class (including the instructor-student accounts) you can remove that test from your class.
Removing a Test from a Class:
1. Login to the site and select your Instructor role.
2. From your Instructor home page, you will click on the name of the class. Then click the Edit Class button.
3. Select the Tests tab.
4. Locate the exam you would like to remove. If no students have started the test there will be a remove button to the right of the test name. Click that, and the test will have been removed from your class.
If students have started the test you cannot remove that test, the remove button will be gone. You can edit the test settings and change the end date/time to the past to prevent more students from taking the test. Click the Edit button and updating your settings.
You can also hide the grade from the grade book so the student's overall grade will not be affected by the test. More information on hiding grades can be found here.