Removing code is easy, just delete those lines. Indeed you may have to update other bits but that's usually trivial (my preferred method is to just work through the compiler errors whenever they pop up).
Then that first piece of code:
You stated before that every tick is 10 cents. Then why adding just 1 cent per pulse?
Also, do you really need to use interrupts? Get rid of that delay(1000) in your code, have a look at "blink without delay" on how to do regular actions without blocking your script, and you can just start to poll the coin acceptor to see whether a pulse is coming in (you will have to add some code to make sure you count each pulse once and only once, only if pulses are extremely short or you have a really heavy workload elsewhere you need interrupts for this).