Most spreadsheet programs should be capable of importing the data from TDL (Tab Delineated Format) and saving them to several other formats, including the plain text file. This will just save the text data without any formatting at all.
Convert Tab Delineated file format to Simple text file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert tdl to txt on Windows
A popular spreadsheet application distributed with Microsoft Office suite
Convert from tdl file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.