User unsubscribed on Q&A topic shouldn’t get email notification when he delete own question

Pre-condition:
1. At least one user should be created and logged
2. User should have VIEW_TOPICS, CREATE_POSTS, CREATE_QUESTIONS and DELETE_OWN_POSTS permissions
3. At least one branch created
4. A branch has Q&A topic where User is author
5. User1 should be subscribed on Q&A topic and unsubscribe on branch