If the valve in question is a product valve (directly tied to a bulk tote), getting it closed is likely a high priority.

The motor can be removed and, depending on how wide open the valve is, you should be able to see that the valve needs to be manually closed (usually with a square socket 3/8"). 

For a throttling valve in a manifold/product stack, you can temporarily remove the motor and open the valve so operations can continue until a motor is replaced.