We study management of localized modes in two-component (spinor) Bose–Einstein condensates embedded in optical lattices by means of changing interspecies interactions. By numerical integration of the coupled Gross–Pitaevskii equations, we find three different regimes of the delocalizing transition: (i) the partial delocalization when the chemical potential of one of the components collapses with a gap edge and the respective component transforms into a Bloch state, while the other component remains localized; (ii) the partial delocalization as a consequence of instability of one of the components; and (iii) the situation where a vector soliton reaches the limits of the existence domain. It is shown that there exists a critical value for the interspecies scattering length, below which solutions can be manipulated and above which one of the components is irreversibly destroyed.