If you don't want to use your Apple ID anymore, you must know first that everything you have bought from apps, music, movies, books, etc. on that Apple ID you will lose access to everything. The same applies to what you have in iCloud, such as photos, contacts, calendar, etc. You must also remember that if you have any active subscriptions, they must be terminated, this also applies to iCloud+
Pictures, files from iCloud Drive can be downloaded from iCloud's Web Page to your computer. You can also export your contacts so you can import them again to a new Apple ID. You will have to manually copy notes into a document on your computer → https://icloud.com
You can cancel your current subscriptions here:
Settings → Apple ID → Subscriptions
If you have an active iCloud+ subscription, you can see how to cancel it here:
Downgrade or cancel your iCloud+ plan - Apple Support
When all subscriptions have been canceled and you have saved what you want from iCloud, you must deactivate Find My iPhone first.
You do this here:
Settings → Apple ID → Find → Find My iPhone → disable.
Also remember to disable iMessages, go to:
Settings → Messages → disable iMessages.
After that, you must sign out of your Apple ID
Settings → Apple ID → scroll to the bottom and select Sign Out.
Now your iPhone is not connected to your Apple ID anymore. You can now freely create a new Apple ID. You can also choose to delete your old Apple ID if you no longer want to use it. This is not necessary, but you may choose to do so. If you have other devices that are signed in to the old Apple ID, then you must also log out of them before you consider deleting your Apple ID.
To create a new Apple ID:
How to create a new Apple ID - Apple Support
Find more information on how to delete your old Apple ID here:
