is there a way to stop mac osx disk encryption in progress?
Solution 1:
Yes, in 10.9+ you can roll it back while its busy encrypting
diskutil cs revert /Volumes/title_drive -passphrase
You will then be promted with the OS X password unlock/decrypt dialog. After that it starts decrypting. The title_drive you can look up with diskutil list or ls -al /Volumes
Check the status with
diskutil cs list
Look for "Conversion Progress" and check if "Conversion Direction:" is set to "backward"