Mashable: Account deletion should be easily accessible within the app, according to Apple's statement.

Apple announced a change in the App Store standards last year that would require all apps that support account creation to have an in-app option for deleting accounts for customers. This requirement, however, has been postponed twice already. As a result, the business has set a new deadline for app developers to implement the new rule in their apps.

As reported by 9to5Mac, until June 30, 2022, all apps in the App Store that allow users to establish new accounts must also include a means for them to cancel those accounts if they so choose. App Store Review Guidelines 5.1.1(v), which defines what apps may and cannot do in terms of account sign-in, explains these changes in depth.

If your app doesn’t include significant account-based features, let people use it without a login. If your app supports account creation, you must also offer account deletion within the app. Apps may not require users to enter personal information to function, except when directly relevant to the core functionality of the app or required by law. If your core app functionality is not related to a specific social network (e.g. Facebook, WeChat, Weibo, Twitter, etc.), you must provide access without a login or via another mechanism

Account deletion should be "easily accessible" within the app, according to Apple's statement. The developer must ensure that the user's tokens have been revoked once the account has been deleted if the app employs the Sign in with Apple feature.

Apps must provide a way for users to delete their accounts fully, not only deactivate them as required by the guidelines. The account's personal information must be removed. Another option to provide users greater control over their data and ensure even more privacy while using third-party apps is by employing this method, it goes without saying.

Here is what Apple officialy stated:

Make the account deletion option easy to find in your app. Typically, it’s included in the app’s account settings.
Offer to delete the entire account record, along with associated personal data. You may include additional options, but only offering to temporarily deactivate or disable an account is insufficient.
If people need to visit a website to finish deleting their account, include a link directly to the page on your website where they can complete the process.
Keep users informed. If the deletion request will take additional time to complete, let them know. If your app supports in-app purchases, help people understand how billing and cancellations will be handled.