Prevent Ember JSONAPISerializer from Sideloading - ember.js

Question

I'm working on an Ember app that consumes an external API and I'm having trouble with my serializer.
My app is ingesting a user account but only cares about the very basics of the user account. The API is publishing much more data, which is causing trouble. Specifically, it is including a relationship to a model which I don't include in my Ember App (because it is domain-inappropriate).
I'm trying to configure my app such that it simply ignores the included and relationship information from the API, but even attempting to delete them from the response in the serializer's normalize hook isn't working. It keeps trying to look up the unwritten model and, obviously, failing. As well, I looked at using DS.EmbeddedRecordsMixin but that seems to still depend on having the related model implemented in my app, which I'm really hoping to avoid!
How do I get JSONAPISerializer to ignore relationships and prevent it from attempting to sideload data from the included object?
To better display my situation, here is an example payload:
{
"jsonapi": {
"version": "1.0"
},
"included": [
{
...references models my app doesn't have
}
],
"data": {
"type": "account",
"relationships": {
"permissions": {
"data": [
...references the included object
]
},
},
"id": "16",
"attributes": {
...this is the information I *do* care about
}
}
}
ETA:
My User model:
// app/models/account.js
export default Model.extend(Validations, {
birthdate: attr('date'),
email: attr('string'),
firstName: attr('string'),
lastName: attr('string'),
profile: belongsTo('profile')
}