Catalyzes the hydrolysis of the phosphopantetheine group from substrate holo-carrier proteins. H2O + holo-[ACP] = (R)-4'-phosphopantetheine + apo-[ACP] + H(+) Deletion mutant is highly and selectively resistant to the amidino-urea compound 1-[(2,6-diethylphenyl)-3-N-ethylcarbamimodoyl]urea (compound 8918). Belongs to the metallophosphoesterase superfamily.