Actually you don't have to unlearn it or relearn it, just find a wast and summon your balverine. Once it's slaughtered the wasp and half killed you, reuse the summon speel and you'll get the wasp back, or you could use it on another animal... the choice is yours...
my advice: don't fret about it too much, the summon spell isn't the only spell in the world, and you've still got those
![G o o d [Good]](/emoticons/g_o_o_d.gif)
ol' magic swords that'll chop your enemies up without ever turning against you!
1 year on the forums and counting! Get it? Counting? Oh never mind...