Ok, there is a lot of discussion about dispelling undead creatures and according to Sage Advice Dispel Magic does not work this way:

Can you use dispel magic on the creations of a spell like animate dead or affect those creations with antimagic field?

Whenever you wonder whether a spell’s effects can be dispelled or suspended, you need to answer one question: is the spell’s duration instantaneous? If the answer is yes, there is nothing to dispel or suspend.

At the same time the Animate Dead description says:

The creature is under your control for 24 hours, after which it stops obeying any Command you've given it. To maintain the control of the creature for another 24 hours, you must cast this spell on the creature again before the current 24-hour period ends.

Although the undead creature has been raised the caster obviously has temporary control over it. Some monsters from MM have an ability to dispel magic which could come in handy for the DM when the party has a necromancer.

Please note: I'm aware of the discussion around whether dispel magic could 'unanimate' an animated corpse. It's clear to me that it couldn't according to RAW. That seems to be what's covered in this related question.

However, I'm asking a different, distinct question. An animator's control of undead is temporary (24hours).

Could dispel magic simply remove the caster's control of the undead, leaving the undead still animated but now outside of the spellcaster's control?

No it does not.

The Dispel Magic description says:

Choose one object, creature, or magic effect within range. Any spell of 3rd level or lower on the target ends.

And Animate dead has a duration of:

Duration: Instantaneous

So there is no spell effect to dispel as Animate Dead has a duration of instantaneous, so as Dispel Magic only works on a spell it has nothing to work on and does nothing. Also clearly stated here stated in this Sage Advice:

Can you use dispel magic on the creations of a spell like animate dead or affect those creations with antimagic field? Whenever you wonder whether a spell’s effects can be dispelled or suspended, you need to answer one question: is the spell’s duration instantaneous? If the answer is yes, there is nothing to dispel or suspend.

The control of the undead granted by the spell is a consequence of the spell being cast, not an on-going magical effect, in the same sense as the fires started by a fireball are an on-going non-magical effect. The zombies are strictly loyal to the caster for a period of time, bonded to them like ducklings are to their mother, and in the same way the fires and damage from a fireball last for a period of time and cannot be dispelled, neither can this bond.

That is a tricky question, asked (at least elsewhere) by a lot of people.

If you go strictly by the rules, spells with a duration of "instantaneous" cannot be dispelled, nor are affected by things like Antimagic Field. This has been officially answered before, at least concerning the general dispelling of undead animated by the spell.

Personally I think this one calls for a DM ruling instead. There is a clear case why a DM could rule that the 24 hour control -effect is something you can dispel or does not work in an Antimagic Field; it has a duration, range of 60 feet and it must be "renewed" by another casting of Animate Dead. Since the undead are controllable only within 60 feet of the caster, as a DM I'd also might rule that the command it was last given, for example "attack the persons in this room" will be carried out "indefinitely" until completed, after which the undead do what the spell says they will do unless commanded (they're not much for thinking for themselves, after all).

But until there is a official ruling, I'd recommend making a house rule and sticking with it.