Working with WordPress theme

First check in your WordPress backend like

1) For Post: xyz.com.wp-admin/post-new.php post where if there is an option to select the template. If this option available then select the “Full Width Template”

2) For Page: xyz.com.wp-admin/wp-admin/post-new.php?post_type=page page where if there is an option to select the template. If this option available then select the “Full Width Template”

3) If above 2 is not available then go to the xyz.com/wp-admin/widgets.php and in right side you can see the “Sidebar” and remove all the widgets from the “Sidebar” box.

I hope this will work for you.