Do I control the rate of decrement by dividing it by 50 and putting a new int value on the declaration?
"it" is a pronoun with no referent. I have no idea what you think you need to divide by 50, or why you want to change the rate of decrement.
You measure how long the switch has been pressed. If it is greater than 1 second, subtract 50 from some value and reset the switch pressed time to now.