Hi, in the function CGMZ_Window_QuestList.prototype.drawQuest remove these 4 lines:

this.changeTextColorForRecLevel(quest._recommendedLevel);
this.drawText(quest._recommendedLevel, rect.x + xOffset, rect.y + this.lineHeight() / 2, rect.width, 'left');
this.changeTextColor(ColorManager.normalColor());
xOffset += this.textWidth(quest._recommendedLevel) + 4;