Note: I had to modify the screen shot to remove domain name of the company.
The drop database command can be useful in a testing environment for cleaning up data files, controlfiles, and log files.
Note: database must be mounted EXCLUSIVE and not open for this operation.
One disappointment is that it did not delete the directory beneath DIAGNOSTIC_DEST.
Here are all the directories still left behind.
This is what I executed to remove the remaining directories in my environment.
find /ora* -user oracle -type d -name PRIME -exec rm -rfv {} \;
ALWAYS be careful when using rm -rf command.
Thinking Out Loud 
