Test Run Assignee can not be removed under Test Run page

Description:  Test Run Assignee can not be removed under Test Run page

Pre-conditions: NA

How to reproduce

1. Create a Test case and add a new Test Execution under it.
2. Execute the Test Run.
3. On the Test Run page, assign it to a user.
4. Now, try to unassign the Test Run, which is not possible. 

Actual result/Attachments: The Test Run assignee is not getting removed. 
bug.mp4

Expected result: The test Run assignee should be removed. 

Version

• 7.8.2

Workaround: We can remove the assignee from Test Execution as shown in the video attached.