Decrypting External Drive

I partitioned an external drive using disk utility & encrypted each partition - "mac osx, extended, journaled, encrypted".

Im thinking of reformatting and partitioning it differently. But there is no option in Disk Utility to do this as it says something like "use command line corestorage...."

Anyone know how to correctly safely decrypt (if necessary) or format and apply new re-partition. I dont need any of the data on the drive so its a just a clean redo.

Thanks.

 

Thanks.