Summary
The Social Q&A is not recommended to use to store How to / procedure articles. You can use the regular knowledge base articles for that.
The Adding New Querstions / Answers are the primary features of Social Q&A. However, if you still like to remove those features you will need to follow the instructions below
Instructions
1. You can open the design view of the following page -
https://<instance>.service-now.com/$spd.do#/sp/editor/sqa_tagged_questions/b967412ad702120023c84f80de61035e
2. Then remove the Add Question button from the page
3. After which, you will have to clone the following widget -
https://<instance>.service-now.com/sp_config?id=widget_editor&sys_id=ca923d81d720120023c84f80de610387
4. the use the clone on the "kb_social_qa_question" page and remove answer and your answer sections from the HTML code of the widget.