How delete a custom propertie ?

[Ludovic Th=?ISO-8859-1?Q?=E9?=bault]

Hello,

I create custom properties in relation with the content of a field :

Fld :              Custom propertie :
Roger          -> ListRoger
Marcel            -> ListMarcel
...

But the content of fld could be changed, and i want to clear the custom
propertie which was in relation with the disapearing text.

I doesn't found any command in the help to do this.

thank in advance

-- 
Ludovic THEBAULT
(Sorry for my poooor english :-)