Do a search for the package in YaST. On the right-hand side panel, click on the checkmark until it turns into an "X". You can also right-click on the checkmark box and select delete.
If the program in question was created by compiling a source tarball, then you need to use the same source to uninstall, by using the "make uninstall" target (as the root user).
If the program wasn't a SuSE package, but installed with the rpm command, and it doesn't show up in YaST, you could try uninstalling it using the rpm command: "rpm -e <package-name>". I think you will still need to run (as root) SuSEconfig after you are finished. This is something YaST would do automatically.
