https://help.ubuntu.com/community/UbuntuReinstallation
I don't know how to open the Installer to get those options.
Also I don't have a CD drive.
https://help.ubuntu.com/community/UbuntuReinstallation
I don't know how to open the Installer to get those options.
Also I don't have a CD drive.
To run the ubuntu installer, you need to create a Live USB.
Instructions for windows are here, and ubuntu here.
Then you change the BIOS boot order to be the USB first. Here, item 3 should be item 1.
Boot it, and you will see the screen that says "Try or Install".
Click install, then choose "Erase Ubuntu 14.04 and reinstall".