It can easily be done
1) Click RESET to ensure you don't accidentally perform other actions
2) View only .zip files by typing *.zip
3) Select SUBFOLDERS if required
4) In 'EXTENSION(11)' set the dropdown option to 'fixed
' and type cbz
in the text area
5) Rename files then deactive 'Extension(11)'
6) In 'Repl.(3)' Set the Replace .zip
and Leave 'With' blank.
- This will now remove the 'extra' .zip in the filename.
Although a 2-stage rename but achieves what you are after.
Bulkrename was originally written for photo file renaming - but can be used for Bulk renaming other files as well.