cancel subscription what will happen to my portfolio website

Your Portfolio website is included with your paid subscription. Adobe Portfolio is a premium feature, so if you cancel your paid membership and return to the free level of Creative Cloud, then the Portfolio website attached to the account would be deactivated.

Which subscription plan do you currently have? Adobe Portfolio is included in all Creative Cloud paid plans... So one option if you were looking to reduce your costs but maintain the website would be switch to a different (potentially lower cost) plan. Here are the options for changing your plan, if that is helpful:

https://helpx.adobe.com/manage-account/using/change-plan.html

Q: What happens when you stop paying for electricity? 

A: The power is turned off.

Q: What happens when you stop paying for Creative Cloud?

A: The service is turned off.

You will need to replace your Portfolio site with a new website and also buy some commercial web server space on which to host it.

There is no forum for that product here, Portfolio help may be obtained at the links below
https://helpx.adobe.com/creative-cloud/how-to/create-portfolio-website.html
https://help.myportfolio.com/hc/en-us
https://portfolio.adobe.com/