Just to let you know, you can only do these things if you are an account administrator or above.
On the Home page, click on the settings icon. From there click on account. Click on the people tab.
As you can see from the example above there is a bin icon, you will need to click on this. You will then be asked to confirm this.
N.B: Retain User's Recordings - If you un-select this, all the recordings associated with the dub.point will be deleted. If the user has any recordings in the future, the recording will be displayed as an Unidentified Dub.Point.