Google Chrome used to have a flag (option) which allowed it to run as a single process, you could start it as Chrome.exe -single-process however they removed that option years ago and it's no longer supported.
Thankfully Chromium still supports the flag and you can invoke it by using --single-process (note the double dash).
In simpler terms, create a shortcut to your chrome portable exe (eg: chromium.exe) and right click, edit. In Linux this option may be called "Make Link". In windows you'll see a path such as "F:\Documents\Chromium.exe", you should edit this to append the flag, so it reads something like "F:\Documents\Chromium.exe --single-process"
On Linux, if you right click on the link and choose Properties, you should see a box saying "Command" use the same logic as on Windows here.
Finally I must quote you this from the Chromium documentation, which you should be aware of before you begin:
The single process model provides a baseline for measuring any overhead that the multi-process architectures impose. It is not a safe or robust architecture, as any renderer crash will cause the loss of the entire browser process. It is designed for testing and development purposes, and it may contain bugs that are not present in the other architectures.
Any problems, reply and tag me and I'll try to clear things up