There is an instance of anaconda navigator already running error

I met the same problem a few days ago. I found the anaconda navigator will start a process called pythonw. So the following is my solution:

1. open a cmd window;
2. use command tasklist | findstr "pythonw" to find the pid of pythonw, like 37200;
3. use command tskill 37200 to kill the process.

By the way, my OS is Windows.