Hey I just found out how to do it I just added this code to qa-theme.php
You no need to do any programing or any modification in your theme. If your theme is built with Q2A standards than use Q2A Market free plugin Hide Sidebar
Find here Hide Sidebar on Q2A Market Store
You might add the following function in your theme's qa-theme.php file:
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.