Just go to My Presets and delete it.
Hitting delete does not work. Right click does not show any option.
After having tried many things, I finaly found that MAJ+Delete works.
Strange, but my issue is solved.
Don't know what MAJ+Delete is, but I'm glad to hear it works for you!
After further investigations, I found out that for an unknown reason, my keyboard had benn customized. I restored the standard Adobe keyboard. Del key works fine now in the Effect pannel.
Sorry for the inconvenience.