Introduction
To completely remove the program, delete:
Applications/Concealer.app
~/Library/Preferences/com.belightsoft.Concealer.plist
~/Library/Caches/com.belightsoft.Concealer
“~” means the user's Home folder.
To delete the card repository from the default location, delete this folder:
~/Library/Application Support/Concealer
To access the Library folder, in the Finder choose Go > Go to Folder (Cmd-Shift-G). Then type "~/Library/" into the edit box, and click the Go button.
To find out the custom location of the card repository, open the Preferences dialog (Cmd-,).
Make sure that the card repository you are going to delete doesn't contain any valuable information.