CEPH: Ceph how to uninstall a Ceph cluster

So... ya f*cked it all up and want to start again - luckily, there's a command for that

# This was run on the ceph-deploy node, in the ~/ceph directory where the keys and ceph.conf were stored. 
cd ceph 
cp ceph.conf ceph.conf.bck
ceph-deploy purge ceph-osd1 ceph-osd2 ceph-osd3
ceph-deploy purgedata ceph-osd1 ceph-osd2 ceph-osd3 # this failed as device/resource busy. guess a reboot will sort but cant tests that atm. to be updated. 
ceph-deploy forgetkeys