We study the phenomenon of many-body localization (MBL) in an interacting system subjected to a combined dc as well as square-wave ac electric field. First, the condition for the dynamic localization and coherent destruction of Wannier-Stark localization in the noninteracting limit is obtained semiclassically. In the presence of interactions (and a confining/disordered potential), a static field alone leads to "Stark-MBL"for sufficiently large field strengths. We find that in the presence of an additional high-frequency ac field, there are two ways of maintaining the MBL intact: either by resonant drive where the ratio of amplitude to the frequency of the drive (A/ω) is tuned at the dynamic localization point of the noninteracting limit, or by off-resonant drive. Remarkably, resonant drive with A/ω tuned away from the dynamic localization point leads to a coherent destruction of Stark-MBL. Moreover, a pure (high-frequency) ac field can also give rise to the MBL phase if A/ω is tuned at the dynamic localization point of the zero dc field problem.