The cancellation of an enrollment application before the effective date can generally be done by the individual applicant themselves or someone who has legal authority to act on their behalf, such as a power of attorney (POA) holder or legal guardian. For example, in the context of Humana plans, only the member or the member's healthcare power of attorney or legal guardian can complete a disenrollment request before the effective date by calling customer care or submitting a written request including the member's information and signature or that of their legal representative. This cancellation can happen anytime before the plan's effective date.

Similarly, for Aetna enrollment applications, clients can cancel before the effective date as well, implying that the person who applied or has proper authorization can make the cancellation.

In summary, once an enrollment application is submitted, it can be canceled before the effective date by the individual who applied or their legally authorized representative (POA or legal guardian). If a specific organization or plan is in question, the exact cancellation procedure and who can authorize it may vary slightly but generally follow this principle.