Hello I erased my phone before unpairing my watch S4 and now I can’t get it paired from the watch app ,it’s like I need to pair with a new watch. The watch itself already has my Apple ID on it though so what do I do ?

Here's an Apple Support article that might help: Unpair and erase your Apple Watch - Apple Support

If you scroll down in the above article, you'll find the section that talks about what to do if you no longer have the old phone. (Essentially what you'll do is erase the Apple Watch and start fresh with the new iPhone).

Hope this helps.

If you have erased your iPhone and also unpaired your Apple Watch without removing the devices from your Apple ID you have two main options.

1. If you know your Apple ID login credentials (user name and password) you can login with a web browser and remove the devices from your ID, then start again as if they were brand new devices. Manage and use your Apple ID - Apple Support
2. If you don't know your Apple ID credentials, please see https://iforgot.apple.com/