[plt-scheme] How to reinitialize the complete search path directory ?

I try to define my own directory for collection without success. 

First, I have defined a collects directory in
C:\Users\amayers\Cours\IFT359\Exercice 

I tried to define PLTCOLLECTS environment variable without success, and I
deleted this environment variable. 

I deleted also the collects directory in 
C:\Users\amayers\Cours\IFT359\Exercice

I logout and login and I still have 
#<path:C:\Users\amayers\Cours\IFT359\Exercice as a collection path

> (get-collects-search-dirs)
(#<path:C:\Users\amayers\AppData\Roaming\PLT Scheme\4.1\collects>
 #<path:C:\Program Files (x86)\PLT\collects>
 #<path:C:\Users\amayers\Cours\IFT359\Exercice>)

I am using version 4.1 on window vista 

Thank you

Andre Mayers