It may be that your account doesn't have full administrator permissions. You should have an 'Organization' option on the left like this.
To clarify, I believe your account needs 'Organization' permissions to be able to delete Administrators. Otherwise you were just likely setup as an Admin of your network which won't give you Organizational powers like add/remove admins.
Adam R MS | CISSP, CISM, VCP, MCITP, CCNP, ITILv3, CMNO
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