how can i change and delete my old apple id from my ipad

Change your Apple ID - Apple Support

and or What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

Are you looking to use an entirely different AppleID account - or instead update your existing AppleID with a new primary email address or other details?

In the majority of cases, creating and using an entirely different AppleID not recommended - as you’ll lose access to any paid Apple Apps, Subscriptions and Services purchased from your old AppleID. All purchases are permanently tied to the AppleID account from where the purchase is made - and cannot be transferred. All of your devices should be signed-in with the same AppleID.

Your AppleID is the key to Apple Services. The account will generally be kept through your lifetime, updating your primary email address (this being the username with which you sign-in to iCloud and other Apple Services) as necessary. Similarly, you should keep your secondary (recovery) email addresses and trusted telephone numbers up to date - as these may be needed if you should ever lock-out your account.

For info:

Change your Apple ID - Apple Support

Change your Apple ID password – Apple Support

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

If you truly wish to use an entirely different AppleID, the most effective method to fully sign-out of services and remove the Activation Lock that with otherwise inevitably cause issues, is to follow this process:

What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

If you haven’t already done so, you may also need to create a new AppleID account:

How to create a new Apple ID - Apple Support