[ubuntu] Deleting folders in Ubuntu 14.04.4

A user can alter or remove files and folders that user owns. But, a user caot do the same with files/folders that user does not own.

You own all the files and folder typically found in your home folder.

It is possible to put files in your home folder that you don't own. One way might be to expand an archive you've downloaded from someplace that contains files or folders owned by the root user.

To alter or delete files you don't own, you need to temporarily acquire the capabilities that otherwise belong exclusively to the root user. That's called "privilege escalation" and, in Ubuntu, it's done with "sudo". You can preface a single command with sudo, or use it as "sudo -i", which escalates your privileges for a period of time. Any command you enter after that will be executed with root's privileges. You'll see that the prompt in the terminal window changes when you do that.

In Linux, files and folders outside your home folder are usually owned by the root user.

Permissions -- who can do what to which files -- can also come into it, but that's more complex.