In my forum I do some events and the awards are some posts that give the AdminCP.

But spent a few days and my users "lost" these posts have given the AdminCP, I believe it is because of the function "recount post" some "task"

How do I disable it?

I wouldn't recommend disabling that task.  I believe it's coupled with some other things. 

You may want to find a different way to award your members than giving them falsely inflated post counts.