If an administrator has not been
assigned for a user then as part of the "Manage your
public data" menu option you can assign any user with an
administrator role as the administrator for a user.

Simply select the required user,
using the list provided and click
.
Please note that you cannot assign
the user to be their own administrator. If you try
to do this then the following error message is
displayed:

If you
get this error then either a) select an alternative user
as the administrator or b) use the
icon to exit from the modify user screen without saving
the changes.