Squarespace and google workspace expert needed for quick backend help!

I'm confident that to a skilled person, this will be simple. To me, this is foreign! I've recently changed my business name (just removed one of the 3 words in the business title). This is posing some challenges for me on the backend. I have a *very* small business but still want things to be running smoothly on the backend. My squarespace website has 3 domains. I want to remove the "main" domain and only keep 2. I also want to ensure that everything on meta business suite is connected correctly. I created an alias on gmail so I can receive emails at both the currently active, and new account in the same inbox. It's been confusing for me to do all this on my own -- ultimately just need some guidance!