In Quest.wz there is a QuestInfo.img node which contains all of the IDs of quests. In the specific quests that appear in the lightbulb, they are triggered by "autoStart", "autoComplete", and "autoPreComplete". The quests that contain these nodes will all have the value of 1 (true/enabled), and you would either make them 0 or remove the node completely. This used to be the method servers had used back in the day to remove the lightbulb, though I personally prefer making the lightbulb transparent.
Example quest:
Code:
<imgdir name="10051">
<int name="area" value="50"/>
[B]<int name="autoStart" value="1"/>
<int name="autoPreComplete" value="1"/>
<int name="autoComplete" value="1"/>[/B]
<string name="name" value="Cassandra's Request"/>
<string name="0" value="#p9010010# wants to talk to you... She's been busy these days teasing #p9000042#. What could she want?"/>
<string name="1" value="#p9010010# says that #b#p9000042##k seems to have become involved in something strange again and asks that you help him. It's about taking care of an egg or something. In any case #p9010010# seems to care about #p9000042# after all..."/>
<string name="2" value="#p9010010# says that #b#p9000042##k seems to have become involved in something strange again and asks that you help him. It's about taking care of an egg or something. In any case #p9010010# seems to care about #p9000042# after all..."/>
</imgdir>