For security, you cannot delete your own member profile (even if you're an admin). Therefore, you'll need another member on your account to delete the member profile for you.

Start by logging into your community website and clicking your name in the upper-right-hand corner. From the drop-down menu, select "Account settings."

Next, visit the "Members" tab, find the member you'd like to delete, and then click on the red 'x' icon under the "Delete" column.

You'll be asked to confirm your decision before the action is taken. Once confirmed, their member profile will be deleted immediately and permanently. For more information on what else happens when a member is deleted, check out this article: Deleting a member.