No., it only ends the spell on a single target
We can extrapolate an answer based on how Dispel Magicdispel magic interacts with spells like Blessbless:
From the Sage Advice CompendiumSage Advice Compendium:
If dispel magicdispel magic targets the magical effect from blessbless cast by a cleric cleric, does it remove the effect on all the targets? Dispel magicDispel magic ends a spell on one target. It doesn’t end the same spell on other targets.
Since the conjure spells actually bring creatures into the Prime Material plane and in essence holds them there, a Dispel Magicdispel magic will only end the magic on a single creaturecreature; the rest would still have the magic to keep them present.