Accidentally Deleted Bootcamp Assistant

Hello there,

I was recently setting up a new SSD with Windows when I accidentally deleted my entire Mac disk. When I looked for bootcamp assistant in my computer, it doesn't exist anymore.

Does this means that I have entirely deleted my Mac OS system? If so, is there anyway I could reinstall the Mac OS?

(I'm not worried about the files, because recently I have moved all my important files into an external hard disk)