There are several issues with those commands.
rmdir only works if the directory to be removed is empty.
If you typed them as in your post, it could not work, as there needs to be a space separating the command name from the parameters.
To make sure that the name of the folder is correctly passed to the terminal, do it like this:
1) Type "rmdir " (without quotes but WITH a trailing SPACE); do NOT press enter
2) DRAG the folder from the Finder and drop it on the Terminal window
3) Press enter
If you get an error, make a screenshot of the command and the error message it and post it here, so we know exacty what is said.