You should be able to cancel some of the extra permits, but you'll have to figure out how many you want to keep soon.
Not sure if you can do it online, but if you call rec.gov they can probably assist in modifying the number of permits before you pay for them.
Holly, unless you want to join Sachiker's group, you won't be able to really use 2 of the spots without him around. If you get stopped on the trail and he isn't around, the rangers will not be happy.