You can always delete the quest, then go back and get it again. This is a frequent tactic for persons getting writs for guild exp. Since the writ-givers can give several different quests, I usually stand there and accept/delete until I get the one I want.
If you don't delete the quest, it will stay in your quest log forever.
Eventually, you will become powerful enough to easily compelte those lower level quests. But don't worry, you will still get the reward.
Here's a insert from the Live Update page at SOE:
*** Questing ***
- An NPC that will offer, update, or complete a quest now has an indicator above its head.
* A quill indicates that the NPC will offer you a quest.
* A book with a quill indicates that the NPC will update one of your quests.
* A book indicates that the NPC will complete one of your quests.
* NPCs that offer a quest 10 or more levels above or below your adventure level will not display these indicators.
* You can turn off these indicators in the Options menu (User Interface -> Name and Chat Bubble -> NPC Overhead Quest Icons).
- Zone maps now display a circle where there is a nearby NPC that offers, updates, or completes a quest.
* NPCs that give a quest are indicated by an open yellow circle.
* NPCs that update or complete quests are indicated by a filled yellow circle.
* Mousing over these icons will show you the name of the NPC.
* NPCs that offer a quest 10 or more levels above or below your adventure level will not be shown on the map.
* You can turn off the quest giver map icons in the Options menu (User Interface -> Game Features -> Show quest icons on map).
- The Quest Journal will now display quest rewards--no more guessing what you'll receive for performing a task. You will also be able to see quest rewards before accepting a new quest.
* Not all quests will show their rewards; some special rewards are meant to be a surprise.
* You can turn off the display of rewards in the Options menu (User Interface -> Game Features -> Show quest rewards).