The uninstall procedure varies with the version of Windows but find it on the Control Panel reached from the Start button (usually at the bottom left of your screen). Make sure you are not running MatchMaker when you uninstall.

If you have installed a previous version, uninstall it before installing Version 2.2.1. Take note first of the details that follow.

When you uninstall MatchMaker Version 2.0, there may be files created by the program that are left over. You can remove these manually, although the program will work if you skip this step.

If you have added your own species, changed species names, or edited descriptions or data, and you wish to retain these changes, the information needed is contained in the files MatchMaker_Added.txt, MatchMaker_Added.dta, MatchMaker_Deleted.txt, MatchMaker_Renamed.txt, MatchMaker_Edited.txt, and MatchMaker_Changed.dta. Contact the authors about the best way to use these files, as there is no automatic process. You should also save any illustrations you have added, because uninstalling will delete the images in the old version.

Otherwise, you can delete these folders (if present):
C:\Program Files\MatchMaker\ (just the MatchMaker folder, not the whole Program Files folder) and
C:\MatchMaker_Data\

This is easiest to do using the program Windows Explorer, found under Accessories under All Programs on the Start menu, or the My Computer program (called Computer in some versions) on the Start Menu. One of these programs may already be on your desktop.

If you have Version 1.31 (or before) installed on Windows Vista or Windows 7, uninstalling that version of MatchMaker might leave leftover files in the folder
C:\Users\username\AppData\Local\VirtualStore\Program Files\MatchMaker\
where "username" is replaced by the name on the account you are using.
Use Windows Explorer or My Computer as in the paragraph above.