1. To remove an empty directory:
rmdir docs
This removes the empty directory docs from the current directory.
2. To remove a directory containing files and subdirectories:
rm -r projectX
This deletes the directory projectX and any files or subdirectories that it holds.
3. To remove a directory interactively:
rm -ir plan9
This will prompt you for confirmation before removing each subdirectory, any files and the directory plan9 itself.