To get a list of all of your boot environments within Opensolaris use beadm like so….
Assuming you know the name of the boot environment that is causing issues you can use the following command (using its name) to remove the ones you think are suss. Note: you need to boot up in the environment that you wish to keep first.
beadm destroy opensolaris-2
If you destroy an environment that is active on boot it will be changed to another be that is available. You can use the following command to set it to a specific boot environment;
beadm activate opensolaris-1
Remember to go into package manager and set the default repository as the preferred again. Update manager may recommend updates from the dev repository still though, remove this repository to prevent this.
Best not to delete a boot enviornment unless you have to.