How to Remove the sidebar in StartBiz Theme for wordpress

I’d like to know how can I finally delete the sidebar in StartBiz wordpress theme beacause I am learning about the possibilities of this beautiful theme but I got stucked with this issue.

Particularly, I want to do than on the blog page for show posts in three columns, and then, every single post without sidebars.

<a href="https://ibb.co/Fz88xWh"><img src="https://i.ibb.co/sqssmPg/1.png" alt="1" border="0"></a>

Thanks!

The page I need help with: [log in to see the link]