My Apple ID is locked and I can’t change it

One option is to delete the apps/purchases made by the other ID and download them using the new ID if desired.

For the old ID.

If this is in the iTunes/App Store, see the 3rd link.

If your Apple ID is locked or disabled - Apple Support.       

If you have changed your ID or password, have you followed the steps in this article?

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

If you see a message that says 'Your account has been disabled in the App Store and iTunes' - Apple Support.    

Contact iTunes Support for assistance. See the Apple Support articles below for contact information.   

iTunes Support – world wide 

Apple Support schedule phone call      

If necessary, try Twitter

https://twitter.com/AppleSupport.          People have posted it may take an hour or more to get a response.

Those purchases are tied to the other ID and can't be transferred. One option is to delete the apps/purchases made by the other ID and download them using the new ID if desired. If necessary, check your purchases history to see which apps/purchases weren’t made by the current ID. 

Purchase History Review.   

Device or computer? Where is it locked? Are you trying to change the email address or unlock the ID? More information would help.

Have you checked Settings/Screen Time for any restrictions?