Cancelling previous schedule

[snippsat]

Is there something going on in the background with schedule which is not being closed down?

Yes you have to use Ctrl+c to shut it down.
Your second code with schedule is line 7 wrong.
Code will not run with that error,look at Cancel a job doc
So a example run.

import schedule
import time

def job():
   print("I'm working...")

schedule.every(10).seconds.do(job)
while 1:
   schedule.run_pending()
   time.sleep(1)

Output:
G:\div_code\answer
λ python 10_sec.py
I'm working...
I'm working...
I'm working...
I'm working...
Traceback (most recent call last):
  File "G:\div_code\answer\10_sec.py", line 10, in <module>
    time.sleep(1)
KeyboardInterrupt
^C

In background there will a process python.exe(python on Linux) running which has a own pid.
If want to see processes in background eg shut down from Python look at psutil.