rm * ---- > Delete's all the files in the current directory.
rm -r * ---> Delete's both the files and the directories in the current directory.

Pls note the above commands don't delete the Hidden Files.

Hidden files are the files which start with .filename , inorder to view the file we need to use the ls -a option.

To delete these files also use a . , i.e:
rm *.*

Note:- All above commands will work only if u have sufficient privileges to do so