Dequeue a queued OpenCL kernel

Dequeue a queued OpenCL kernel

I need to dequeue a queued OpenCL kernel, if order to free GPU resources.
Is it even possible?
What I am doing is queueing a kernel and a I/O copy. Then check in the
host side if this result is correct or not. But since 70% of the time is
not correct, I queue another run while I check for the result in the host
(CPU+GPU is parallel!). This way the GPU is 100% in use.
However, as soon as I found that the result is correct I can't cancel the
ongoing kernel. With is wasting GPU resources.
I am using many OpenCL queues and kernels in parallel, so this is
effectively slowing me down and putting the bottleneck in the GPU. Is it
even possible to dequeue that kernel?
Thanks.