Redirect to Main URL from /wp

I have done this with my other sites but I cannot recall how I did it.

I installed WP on a new site and now the domain is located at domainname.com/wp instead of domainname.com.

I simply cannot figure out how to redirect the site to domainname.com.

I’ve reread the article on .htaccess and for some reason (perhaps old age?) I just cannot fathom how to do what needs to be done. If anyone can simplify this for me I will be grateful. Thank you.