The cross section for one-proton knockout from 14O on a carbon target at 305 MeV/nucleon was measured to be σ−p(14O→13N)=35(5)mb. The one-proton one-neutron (pn) removal cross section σ−p−n(14O→12N)=30(6)mb and two-proton one-neutron (2pn) removal cross section σ−2p−n(14O→11C)=41(6)mb were also obtained. The deduced reduction factor, the ratio of the experimental and theoretical cross sections, is close to unity for one-proton knockout from 14O, consistent with the systematics as well as the result obtained at a much lower beam energy. The indirect reaction process, which involves a one-neutron knockout plus proton(s) evaporation mechanism, is expected to contribute much to the pn and 2pn removal.