Effects of dipolar and spin-exchange interactions are entangled in spin-1 Bose-Einstein condensates, due to their coexistence.We propose to independently manipulate the magnetic dipolar and the spin-exchange interactions by applying generalized WAHUHA sequences of rf pulses and by applying periodic dynamical decoupling sequences of optical Feshbach resonance pulses, respectively.While suppressing one interaction, we can make the other interaction dominate the spin dynamics in the condensates.Furthermore, by suppressing both interactions, this method can be harnessed to realize spinor-condensate-based magnetometers with a higher sensitivity.