This should resolve the issue with delete, the problem comes from the path set by FlashFXP not matching the path returned by the FTP server. The path is now updated to match the case of the folder created on the server. Due to this case mismatch the folder cache wasn't being cleared and FlashFXP was displaying a stale directory listing.
http://www.flashfxp.com/testr/ffxp-dev-build.zip