If you have the original installer, then the Uninstall (under Custom Install) would be the quickest way, just like RWoelk says. If you do not have the installer:
Throwing out the application will technically do it. There will be a few files left over, but they will not mess up your system.
There will be a preference file with the same name as the application in System Folder/Preferences. Harmless, but you can throw it out to tidy up.
There may be extensions in the Extensions folder, these could waste processor time and make bootup take a bit longer. Use the Extension Control Panel, sort by "Package". This will show what installer installed each, look for the unwanted application name as the installer.
There may also be a file/folder in System Folder/Application Support. There are a few other places to check as well like Startup Items, Help, Control Strip Modules, Contextual Menu Items. Check them if you like.