Error EPERM: WARNING: this will *PERMANENTLY DESTROY* all data stored in pool new.default.rgw.buckets.data.  If you are *ABSOLUTELY CERTAIN* that is what you want, pass the pool name *twice*, followed by --yes-i-really-really-mean-it.

Droping a pool:

ceph osd pool delete ${POOL_NAME}

Will result in the upper message:

Error EPERM: WARNING: this will *PERMANENTLY DESTROY* all data stored in pool ${POOL_NAME}.  If you are *ABSOLUTELY CERTAIN* that is what you want, pass the pool name *twice*, followed by --yes-i-really-really-mean-it.

So:

ceph osd pool delete ${POOL_NAME} ${POOL_NAME} --yes-i-really-really-mean-it

That by default will show a message:

Error EPERM: pool deletion is disabled; you must first set the mon_allow_pool_delete config option to true before you can destroy a pool

So you need to change that parameter prior to dropping the pool:

ceph tell mon.${x} injectargs '--mon-allow-pool-delete=true' 

Where ${x} is the master monitor (I suppose any mon on the pool will propagate the setting).
Then drop the pool:

ceph osd pool delete ${POOL_NAME} ${POOL_NAME} --yes-i-really-really-mean-it

And re-set the parameter, THIS IS MANDATORY:

ceph tell mon.${x} injectargs '--mon-allow-pool-delete=false'