Thanks for reaching out.
Just follow the following steps
1) Go to theme root folder ie wp-content -> themes -> purea-magazine
2) Again go to inc -> customizer -> options -> section-footer.php
3) Open this file with any text editor and then change line text from
‘sanitize_callback’ => ‘purea_magazine_sanitize_textarea_field’
to ‘sanitize_callback’ => ”
4) Save the file.
PS: Make sure to repeat the steps if you update the theme.