Porsche Boxster Owner's Manual page 185

Note
Several attempts with different distances between
the vehicle and the hand-held transmitter might be
necessary.
The fog lights will flash once the 5 minutes have
been exceeded. Programming must be repeated
from the beginning in this case.
Deleting programmed signals of the HomeLink
(e.g., when selling the vehicle)
Keep the two outer buttons 1 and 3 depressed
for approx. 20 seconds until light-emitting diode A
begins to flash quickly. All programmed signals of
buttons 1 to 3 are deleted.
183
Controls, Instruments