There is no container available with the name friendlyhello as you are simply running the container using docker run -p 4000:80 friendlyhello, here friendlyhello is the name of the image, and not the container’s name.
Either run that container by giving it a name like below:-
docker run -p 4000:80 --name SOMENAME friendlyhello
In this case you will be able to stop and remove that container using the below command
# container stop
docker container stop SOMENAME
# container removal
docker rm -f SOMENAME
Or if running without giving a name to the container, you will have to use the ID of the container in the commands to stop and remove, even in various other commands you will be using the ID to refer that con