[Change Wanderer's Skill to use without Duet]

Hi,
I would like to know how I remove duet from a skill

Example:

 case WM_MELODYOFSINK:
    case WM_BEYOND_OF_WARCRY:
        if( flag&1 ) {
            sc_start2(src,bl,type,100,skill_lv,chorusbonus,skill_get_time(skill_id,skill_lv));
        } else {    // These affect to all targets arround the caster.
            if( rnd()%100 < 15 + 5 * skill_lv * 5 * chorusbonus ) {
                map_foreachinrange(skill_area_sub, src, skill_get_splash(skill_id,skill_lv),BL_PC, src, skill_id, skill_lv, tick, flag|BCT_ENEMY|1, skill_castend_nodamage_id);
                clif_skill_nodamage(src,bl,skill_id,skill_lv,1);
            }
        }
        break;
	

I wish this skill didn't need Ministrel, if anyone can help me I will be grateful