Thx for your answer... however to delete the Bluetooth connection, I had to desinstall the bluetooth devices, and then reinstall.
The pb is still there : BB8310 is bluetooth enabled, set to discoverable, then I start the add bluetooth device process on the computer, it detects the BB8310, asks for a key, I enter a numeric key, the key is then asked for on the BB8310 and the the BB goes to "unable to pair" while the computyer says something meaning (sorry that's in French) time to enter the access key excceeded.
What do I do wrong ?