Sign in with different account

Sign out on your iPhone, iPad, or iPod touch

1. Go to Settings > [your name]. 
2. Scroll down and tap Sign Out.
3. 
4. Enter your Apple ID password and tap Turn Off.
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.

On your Apple ID account page

1. Go to appleid.apple.com and sign in.
2. In the Account section, click Edit.
3. Under your Apple ID, click Change Apple ID. ...
4. Enter the Apple ID that you want to use.
5. Click Continue.

Change your Apple ID – Apple Support