Cold Wave and Magical City: Endymion(Disneyland).

If Cold wave is activated while Magical City: Endymion(Disneyland) has Magic Counters, will the Magic Counters be removed?

nope

Ok thanks.

if the citadel card is already played and say it has 4 counters.
and then you activate cold wave. but since the citadel field card is already played,
can you still remove counter from the field card for your monsters effect.

like breaker, can you still remove a spell-counter but from the field card, since it says you can on the field card.
or does cold wave prevent that???

From wiki:

The current errata of "Cold Wave" is "This card can only be activated at the start of your Main Phase 1. Until your next Draw Phase, neither play can Set nor activate the effects of Spell and Trap Cards.". Thus, while the effect of "Cold Wave" is active, neither player can,[3]

* set Spell and Trap Cards from his hand.[3]
* activate Spell and Trap Cards from his hand.[3]
* activate Spell and Trap Cards which are Set in the Spell & Trap Card Zone.[3]
* activate the effect of Spell and Trap Cards which are already face-up on the field, such as the effect of "Wave-Motion Cannon"[3]

Cold wave prevents that.