You have to edit footer.php file located at wp-content/themes/your-current-active-theme. In footer.php file find <p>© <?php echo esc_html(date('Y')).' '; bloginfo( 'name' ); ?> | <?php printf( esc_html__( 'Theme by %1$s', 'financeup' ), '<a href="'.esc_url('https://www.themeansar.com').'" rel="designer">Theme Ansar</a>' ); ?></p>and replace it with <p>© <?php echo esc_html(date('Y')).' '; bloginfo( 'name' ); ?> </p>.
Note : All Changes you done in footer.php or other file are gone when you update theme. So prefer Child Theme
+https://wordpress.org/support/topic/how-to-delete-copyright-of-theme-ansar-in-footer/