Wall of Ashes uses per day

[hellhamster]

How many times per day Cleric can use "Wall of Ashes (Su)" ability from Ash subdomain

"You can use this ability for a number of minutes per day equal to your cleric level, but these minutes do not need to be consecutive."
But how many walls per day i can create? Is it dismissal?

[Claxon]

This ability isn't limited by times per day, it's limited by a duration.

You can create a wall and sustain it for a number of minutes equal to your cleric level, but each usage uses a minimum of 1 minute even if you only use it for 2 rounds (10 seconds). The minutes do not need to be consecutive.

So, effectively a 10th cleric could use this ability 10 times in 1 day, each time for 1 minutes. He could also only use it 1 time for 10 minutes in 1 day.

[hellhamster]

1) Is it dismissal, when i have to define duration for this wall? When i cast it?
2) Can i have more than one wall at the same time?

[Pizza Lord]

Like Claxon has said, you can use it as many times per day as you have minutes. While I don't see it written specifically in the ability you linked, the typical wording is that it will use at least 1 minute of duration minimum. So you have your answer from him.

Is it dismissible?
Since I see nothing that says you must concentrate to keep the wall up, you would either have to dismiss it or it would just remain until your daily duration expired.
Can you have more than one?
I don't read it as such, no. One wall at a time. I would assume that creating a second one will automatically end the first, so you could at least save yourself the standard action from Dismissing the effect if you needed to move or place a new wall in a new location.

While it's possible that a reading might seem to allow multiple walls in existence at once, the mechanic for time-keeping would get a bit more unwieldy than the system usually handles duration. You'd have multiple walls draining increasing amounts from the duration pool. Say you're 10th-level, you have one wall, it's out for 1 minute. You have 9 minutes of duration left, you create a 2nd wall. 1 more minute passes you now have 7 minutes of wall left. You make a 3rd wall, and another minute passes, you've now spent 6 minutes of duration, but only 3 minutes have passed... it may seem easy enough while reading it and in minute durations, but in situation like that you would be going in rounds most likely and it would get confusing quickly. Likely it's best to just assume one wall at time.