1. We need a child theme for Listivo: 

How to use Child Theme? How to change files (php / css / js) and keep theme future update compatibility?

 2. Add this PHP code to the functions.php file: 

remove_filter( 'the_content', 'wpautop' );
remove_filter( 'the_excerpt', 'wpautop' );

function aiooc_crunchify_wpautop_nobr( $content ) {
return wpautop( $content, false );

add_filter( ‘the_content’, ‘aiooc_crunchify_wpautop_nobr’ );
add_filter( ‘the_excerpt’, ‘aiooc_crunchify_wpautop_nobr’ );

3. Results:

This code removed p tag when you hit enter.