Apple ID

If you delete all but one, you will lose the data and the purchases made with those IDs. You can try setting up Family Sharing between the IDs if you want to be able to share purchases made with the IDs.

Family Sharing.   *

ASC YouTube for Family Sharing

Family Sharing - Set up.  *

Family Sharing - Set up on iPhone.  -

Family Sharing - Set up Family Sharing in the Apple TV app.  -

Family Sharing - parent or guardian designate.  -

Family Sharing - Use your own Apple ID for Family Sharing     *

If you want to delete all but one anyway, all purchases made using an Apple ID are tied to the ID. Delete the ID and you will need to download them using your new ID. Once your Apple ID is deleted, you can't use the email address that you used with it to create a new Apple ID. In addition, you can't use that email address with another existing Apple ID except as a rescue email. Also, if your primary Apple ID email address is with a Custom Email Domain, it can never be reused to create an Apple ID after your Apple ID is deleted, even if the domain ownership changes..  Make sure that you sign out of all your devices to avoid issues with apps that use your Apple ID account or iCloud. After your account is deleted, you can't sign out of iCloud or turn off Find My iPhone Activation Lock on your devices. If you forget to sign out, you might not be able to use your device when your account is deleted.

How to delete your Apple ID account.   *  

Apple ID – How to Delete.  -

Delete Apple ID (new).   -

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