Simply unzip the distribution somewhere. Example:

C:\> unzip temp\xfc_pro_dotnet-6_5_0.zip
C:\> dir xfc_pro_dotnet-6_5_0
...
bin     <DIR> ...
doc     <DIR> ...
legal   <DIR> ...
samples <DIR> ...

This means that uninstalling XMLmind XSL-FO Converter simply consists in deleting the directory created by unzipping its distribution.