From the list of Members, you can modify the management Level by clicking "Edit".

In the editing window, you can also delete the Member.

You can also delete the member by selecting the red "-" button shortcut in the list.

Once a member is deleted from the list, the Site will not be displayed as a Home in his or her WiZ app any longer when the WiZ app refreshes the session.

Note that being removed from a Site is only done when the WiZ app refreshes the session, which is dependant on the member activity (it can take some time to be applied).