When a neutral mob like a Wolf or a Bee is angry at an entity, you can't calm it down by manually reseting both NBT responsible of this behavior which are AngryAt( and AngerTime), except if the mob isn't able to reach you anymore (if you're in creative mode for example, or far enough from the mob).

• Trying to remove only AngryAt nbt will fill it back the tick after with the previous target UUID.
• Trying to set AngryAt on any value (0 or 1 or whatever) will fill it back the tick after with the previous value.
• Trying to reset both nbt in the same tick (in any order) will still refill both nbt with their previous values.

How to reproduce:

1. Turn yourself in Survival or Adventure mode.
2. Summon a wolf

   summon wolf

3. Hit the wolf
4. Run those commands separatly or simultaneously (in the same tick) with command blocks or chat, or with a datapack function:

   data remove entity @e[type=wolf,sort=nearest,limit=1] AngryAt
   data modify entity @e[type=wolf,sort=nearest,limit=1] AngerTime set value 0
   

-> The wolf will still be angry.
(You can see that both nbt have take their old values using the "/data get" command)

Re-iterate the whole operation, but set yourself in Creative mode between the step 3 and 4.
Since the wolf isn't able to reach you anymore, you'll see that running the command of the step 4 will calm the wolf.