How to delete a non-empty directory in Terminal

rm -rf lampp

It deletes all files and folders contained in the lampp directory.
Add sudo at the beginning of the command :

In case user doesn't have the permission to delete the folder:

sudo rm -rf folderName

Otherwise, without sudo you will be returned permission denied. And it's a good practice to try not to use -f while deleting a directory:

sudo rm -r folderName

Note: this is assuming you are already on the same level of the folder you want to delete in terminal, if not:

sudo rm -r /path/to/folderName

FYI: you can use letters -f, -r, -v:

• -f = to ignore non-existent files, never prompt
• -r = to remove directories and their contents recursively
• -v = to explain what is being done