I added a user just for learning purpose how to add user using the command
sudo useradd usernamefollowed by my password, the user is created successfully.
Now I don't want it and running the command
sudo userdel username in terminal, instead of removing the user it is showing
userdel: user sonu is currently used by process 13404.
Also I tried to remove it from user & accounts option in all setting there it is showing running
'/usr/sbin/userdel' failed: Child process exited with code 16.
now I've no idea how do I remove this unwanted user.