Unsetting ZFS options can sometimes be a bit murky (at least for me.) Sometimes you remove them with

zfs set property='inherit[ed]' fsname

Which resets that property to the parent’s value for that particular ZFS filesystem. However, the share options are not done that way. Instead you need to use

zfs set -c property="values to unset"

So, first you need to get the name of the share with zfs get:

zfs get share

Which will list the values of the share property for all ZFS pools, like this:

storagetank  share   name=storagetank,path=/storagetank[...] local

And then you unset them like such:

zfs set -c share='name=storagetank' storagetank

Which will remove the share, allowing you to re-create it with the correct settings.