O artigo A exclusão de cookies do Safari via AppleScript sugere esse script para excluir os cookies de três sites específicos:
set deCookie to {"nytimes.com", "go.com", "cnn.com"}
tell application "System Events"
tell process "Safari"
keystroke "," using command down
delay 1
tell window 1
click button "Privacy" of tool bar 1
delay 3
repeat with d in deCookie
click button "Details…" of group 1 of group 1
try
keystroke d
delay 1
select row 1 of table 1 of scroll area 1 of sheet 1
click button "Remove" of sheet 1
end try
click button "Done" of sheet 1
end repeat
end tell
keystroke "w" using command down
end tell
end tell
Escrito em 2013, talvez seja necessário adaptar esse script ao Safari 8.