iRule to delete the cookies

Do you mean the APM session or other SSO cookies, try testing this or feel free to customize if you know the cookie name.

ltm rule remove_logout_cookie {
when HTTP_REQUEST {
  set logging_out 0
  set cookie_names [HTTP::cookie names]
  if {[string tolower [HTTP::path]] ends_with "logout.php" } {
    set logging_out 1
  }
}
 
when HTTP_RESPONSE {
  if { $logging_out == 1 }{
    foreach cookie_name $cookie_names {
	  HTTP::cookie remove $cookie_name
    }
  }
}
}