How can I log into my old Apple Music account... so no longer want to do the family sharing

First --> Leave Family Sharing - Apple Support

Follow the steps below.

Update your devices

Update your iPhone or iPod touch to the latest version of iOS, iPad to the latest version of iPadOS, or Mac to the latest version of macOS. On a PC, make sure that you have the latest version of iTunes for Windows.

Open Apple Music

On your iPhone, iPad, iPod touch, or Mac, open the Apple Music app. On your PC, open iTunes for Windows.

Then tap or click For You.

Start a trial

Tap or click the trial offer to get started. (One trial per person or family.)

Choose your subscription

Choose the type of subscription that you want.

Enter your Apple ID and password

Tap or click Use Existing Apple ID, then enter your Apple ID and password. If you don’t have an Apple ID, tap or click Create New Apple ID, then follow the steps to create one.

If you're not sure if you have an Apple ID, we can help you find out.

If you're asked for a verification code, you have two-factor authentication on your Apple ID. Learn about two-factor authentication and what to do if you still can’t sign in.

Confirm your details

You might be asked to confirm your billing information and might need to add a valid payment method. Then tap or click Join.*

If prompted, agree to the terms and conditions.

*Learn how to verify your age when you join Apple Music in South Korea.

Start listening

Open the Apple Music app, then search for an artist or song. On a PC, open iTunes for Windows.

To find music recommendations based on what you listen to, go to For You. Go to Browse to check out new releases, chart-toppers, curated playlists, and more.