Okay. When you typed out, "Erase What?," I figured I should reply again. I will erase/remove this command, sudo apt install c9-core-installer, with this command, sudo apt remove c9-core-installer. Then, I used sudo apt autoremove.
Oh and right-o. March 1st! A new beginning, I have a ton of work already done on this board. I do not want to risk errors until after the local Maker Faire.
P.S. I will get the updated image later on in the month. Thank you for replying. Oh and when you typed, "It's already installed by default..," I erased it listening to another person once upon a time. I lost bonescript, cloud9 IDE, and the sockets that made them work.