Both cyclists were fired late Thursday, but the withdrawal happened before Friday's 13th stage of the race.
Ricco, 24, tested positive for the blood-boosting drug EPO while Piepoli, 37, was dismissed because of a "violation of the team's ethics code," the BBC said.
Ricco won two stages at this year's event but was given a police escort on Thursday while Piepoli won stage 10.
"(Team manager) Mauro Gianetti has lost faith in them and decided to fire them from the team," said Saunier Duval spokesman David Garcia in a statement. "(Gianetti) did a personal investigation and consequently lost faith in Ricco, but also in Piepoli because of a violation of the team's ethics code."