Cancelling subscription on one linked account

[HIWCF_Jo]

My organisation has 2 accounts which are linked. One is the Owner, one is the Admin.  We want to cancel the admin account as we are no longer using it.  How do I cancel the subscription and delete the admin account without affecting the Owner account which we use all the time.  And do I have to unlink them before doing anything so as not to affect the Owner account which we are using. Thank you.