Help with someone over my AppleId

Can you please provide more detail? It is in fact possible to use a different Apple ID in various places on a device, although one will be the "main" one. That's the one that appears under Settings at the top. If this is incorrect, sign out of the old one and sign in with the other one. We could provide more complete information if we knew what exactly you meant when you say it isn't your main Apple ID.

Read this document to learn how to sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac --> Sign out of iCloud on your iPhone, iPad, Apple TV, or Mac - Apple Support

For an Apple mobile device:

1. Go to Settings, then tap your name. 

2. Scroll down to the bottom.

3. Tap Sign Out.

4. Enter your Apple ID password and tap Turn Off. (Read this if you If you forgot your Apple ID password - Apple Support ) 

5. Turn on the data that you want to keep a copy of on your device.

6. Tap Sign Out.

7. Tap Sign Out again to confirm that you want to sign out of iCloud.

Read this support article to learn how to sign in with your Apple ID on various kinds of devices --> Sign in with your Apple ID - Apple Support

For an Apple Mobile device:

1. Open the Settings app.

2. Tap Sign in to your [device].

3. Enter your Apple ID and password.

4. If prompted, enter the six-digit verification code sent to your trusted device or phone number and complete sign in.

You can only be logged in at one Apple ID per device. So go to settings>your name to see if you're logged in with the correct Apple ID