How do I remove a pool from ZFS?
sudo zpool destroy rdata
will destroy the old pool (you may need -f to force).
sudo zpool export rdata
will disconnect the pool.
sudo zpool import 7033445233439275442
will import the new pool. You need to use the id number as there are two "rdata" pools.
As you're running with a ZFS root, all that's left to do is rebuild the initramfs to update the pools:
sudo update-initramfs -c -k all
sudo update-grub
Reboot and all is well. :)