End concentration?

[guppy]

Is there an easy way to end concentration on a spell early without casting a new one?
TT rules is that you can do it at any time as a free action, so I'm properly just missing something obvious.

"why?"
If I eg. blocked a path with "cloud of daggers" and want to move though it with out killing my party :)

[Fizzgig]

Just underneath your character portrait at the bottom of the screen is an icon with the spell. If you click on that you can end the spell.

[guppy]

thanks