Hi Syedmuksit,
Thanks for choosing IntellyWP products.
Currently you cannot modify this parameter using our Admin user interface but you can do it directly modifying the template css/html code.
You can modify the file youtsite/wp-content/plugins/intelly-related-posts/assets/templates/styles.html in the below way:
Row: 48
From:
text-decoration: underline!important;
To:
text-decoration: none!important;
Please keep in mind that this file will be updated each time that we publish an updated version of this plugin so you will lost your modifications.
Let us know, Alex.
You are welcome in IntellyWP