rm

rm stands for remove. rm command is used to remove objects such as files, directories, symbolic links. By default, it does not remove directories.

Interactive deletion - will ask for confirmation:

rm -i file.txt

Remove the file forcefully - overrides minor protection, if file is write protected:
rm -f file.txt

Recursive deletion - performs a tree-walk and delete all the files and sub-directories recursively of the parent directory. Can be used to delete directories:
rm -r directory

Add -v option for verbose output:
rm -vr {test1,test2,test3}