Cancellation of some of my iTunes In-App purchase?

You can cancel your subscriptions by following the steps mentioned in this related article:

If you want to cancel a subscription from Apple - Apple Support

In case you purchased the In-App purchase directly from the developer, you might have to contact them again, to cancel it.

How to contact an app developer - Apple Support

Hi,

I see you want to void some purchases you have made such as in-app purchases. These could be either subscriptions or purchases of services or consumables.

You can cancel a subscription, but you cannot "cancel" a purchase such as an in-app purchase. However, you can ask for a refund for purchases or subscriptions. Read this article for how to request a refund for apps or content that you bought from Apple - Request a refund for apps or content that you bought from Apple - Apple Support

Note that although you can request a refund, Apple starts from the position that all transactions are final and it does not have to grant all refund requests.