To delete an existing test case: 

1. From the Test Cases page, initiate deletion by either:
   • Identifying the test case to delete, clicking the dropdown arrow at the right end of the row, and selecting Delete.
     Or:
   • Selecting the checkbox of the test case to delete and clicking the Delete (trash can) icon.
2. Click Ok to delete the test case.

The Force.com multitenant architecture limits cascading deletes to 100,000 combined object records. Before deleting a test template or test case you suspect might have more than 100,000 associated records, first delete the associated test runs to avoid causing a situation that requires the assistance of Salesforce support. Refer to the Delete Operation Too Large Salesforce knowledge article for details.