Is their anyway I can switch from Ubuntu 64-bit to Ubuntu 32-bit easily without replacing the whole OS.
No, I don't think so. You will have to reinstall the entire OS (the root partition, to be precise.). The packages and the kernel will have to switch back to the 32-bit version. At the most, you can keep the same home directory, so you don't lose your settings, bookmarks, Music, Photos, etc.