Simply unzip the distribution somewhere. Linux/Mac example:

~$ cd /opt
/opt$ unzip /tmp/xfc_pro_java-6_4_3.zip
/opt$ ls xfc-6_4_3
bin/
doc/
ext/
legal.txt
legal/
samples/

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