Lots of applications have uninstallers but some don't and others leave stuff behind. This procedure should ensure you have nothing left of an application:
Launch Finder and search the hard drive for the app name:
Delete all files and folders related to the app
Don't empty the Trash until restarted and confirmed all ok e.g. for a week
- Load Activity Monitor and change "My Processes" at the top to "All Processes
- Ensure the app you want to remove is not running. Quit it if it is.
- If it automatically relaunches: check if the app is set to automatically launch on startup and delete:
- System Preferences, Users & Groups, [username], Login Items
- Finder: select Go, Go to Folder, /Library/LaunchAgents
- Finder: select Go, Go to Folder, ~/Library/LaunchAgents
- Finder: select Go, Go to Folder, /Library/StartupItems
- Once you've removed the app from the startup list, restart
- Select View, "As List"
- Click the + button below search and select:
- "Name" "Contains", enter the app name
- "Other...", "System files", select "are included"