Skype does not permit an account to be deleted once it is created; here is step-by-step instruction how to abandon the account: https://support.skype.com/en/faq/FA142/Can-I-delet
Sign into your account and cancel your subscriptions. Then you may apply for a refund: request a refund
Re: accounts that become dormant or in-active ... do remember your Skype account name, the password, and the registered e-mail address. If you decide to use the account sometime in the future, and you forget the password, you will need to provide details such as the registered e-mail address and information from the method of payment used to purchase subscriptions or credit in order to establish your identity.
Please remember that we here in this Skype user-to-Skype user Community are not authorized to address account-related matters. Account-holders or account "owners" must contact Skype Customer Service themselves. contact customer service
I think that about covers it!
Some additional suggestions here;