A. Unlink a Single Test Case: Hover the mouse over the test case, which you want to unlink. The Unlink icon becomes visible. Click on the Unlink icon.
B. Unlink Multiple Test Cases: Select the test cases that you want to unlink from the story and click Bulk Unlink.
Refer to Unlink Stories from Test Case.
Refer to Unlink Test Cases from Test Cycle.