You can kill Applications by using Activity Monitor.app, being the GUI solution. That would be a simple "force quit". However, that doesn't always work out for different reasons in some situations!
The command-line solution as mentioned in the comment above holds a lot more options for the user.
sudo killall Python or if it is a running program-process
sudo killall /Applications/Whatever.app forces the the process to quit as well.
You can also force a process to quit, using its assigned PID. In the case of Activity Monitor.app it would be
kill 25794 or
kill -9 25794
Some more details:
The kill program in Terminal simply force quits a program, as though by remote control. (It even works when you SSH into your Mac from a remote location. Follow the kill command with the process ID number (short PID) of the program you want to terminate.
Unless you also use sudo, you can kill only programs you “own”—those running under your account. (The operating system itself—root—is always running programs of its own, and it’s technically possible that other people, dialing in from the road, are running programs of their own even while you’re using the Mac!)
-9 flag is a “non-catchable, non-ignorable kill.” In other words, it’s an industrial-strength assassin that accepts no pleas for mercy from the program you’re killing.