Since I can't remember my old account. How do I reconnect to my new apple account.

I had an issue since I can't remember my old iphone password so I restored it and after that I was faced with a even bigger issue, my old icloud sign in.

Have you forgotten your password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

I went ahead with creating a new apple account. Now I'm stuck at how to remove the iphone from old apple account so I can connect it with the new account.

It is not possible to merge multiple Apple ID accounts.