A deactivated pool can be erased by using the -e option of the pool_tool command. Using pool_tool -e erases the disk labels written when the pool was created.
pool_tool -e [PoolName]
Specifies the pool to erase. If no pool names are specified, all pools are erased.
This example erases all disk labels for pool0:
pool_tool -e pool0
The -O (override) flag bypasses the confirmation step.