Is there any way I can end the duration of a spell early?

[Rogar Stonebow]

Which book and page number for source if answer is yes.

[bbangerter]

Couldn't tell you the page number, no book with me atm, but under the magic chapter.

prd wrote:

(D) Dismissible: If the duration line ends with “(D),” you can dismiss the spell at will. You must be within range of the spell's effect and must speak words of dismissal, which are usually a modified form of the spell's verbal component. If the spell has no verbal component, you can dismiss the effect with a gesture. Dismissing a spell is a standard action that does not provoke attacks of opportunity.

A spell that depends on concentration is dismissible by its very nature, and dismissing it does not take an action, since all you have to do to end the spell is to stop concentrating on your turn.

[RedDogMT]

Some spells can be ended early. You will find the answer in the Duration sub-section of the Magic chapter of the Core Rule Book:
(D) Dismissible: If the duration line ends with “(D),” you can dismiss the spell at will. You must be within range of the spell's effect and must speak words of dismissal, which are usually a modified form of the spell's verbal component. If the spell has no verbal component, you can dismiss the effect with a gesture. Dismissing a spell is a standard action that does not provoke attacks of opportunity.

Here is a link to the info in the PRD: PRD LINK.

Other spells end when their duration is up unless they are dispelled.

[King of Vrock]

You can also choose the spell to function at a lower caster level if you want it to last a shorter than normal duration. This might work better for the few spells that are not dismissible.

[Rogar Stonebow]

Hey guys thanks for your help.

[StreamOfTheSky]

If the spell is not dismissable, note that you can choose to automatically succeed w/ Dispel Magic at dispelling a spell you cast.

Dispel Magic wrote:

You automatically succeed on your dispel check against any spell that you cast yourself.