How to Activate the New Site
In the best case the new site just builds. But I believe the github pages need to be activated.
The next part is converting to your projects site. This documentation will be active in the new site. To remove it you could delete the entire folder context/posts or delete all the posts. You will likely need to have a local hugo setup to allow local development of your site.
This post will likely be revised with the actual activation instructions.
How to enable github pages
The new site needs github pages enabled. Select the repo's setting page, the Setting gear. User the sub heading on the left that says "Code and Automation" and select the Pages item. The next dialog will have a header Build and deployment dropdown menu called Source. Change the Source to Github Actions. That action is defined by this repo in .gitub/workflows/Hugo.yml.