sme to text conversion most likely represents attempts to export messages / contacts from a .sme backup (Samsung Kies) to a text file (typically some structured format, such as CSV). Such export should be doable with Samusung Kies, or at least in some of the older versions of the utility.
Some other programs, for example the SmartEncryptor also use .sme files, but it is unlikely that these encrypted archives can be exported to some text format (.txt) directly. Perhaps it is possible that some text files are located within the encrypted .sme file. If that's the case, you will need to decrypt and extract the archive using SmartEncryptor, no converter will help you.Open SME file Open TEXT file