Axios.delete() not triggering as expected - node.js

Question

So I've got a classes Model which contains an array of people who will attend the class, I am trying to remove people from the classes.
So this is the Model:
const mongoose = require('mongoose');
const classMembersSchema = mongoose.Schema({
userId: {
type: mongoose.Schema.Types.ObjectId,
ref: 'user',
}
})
const classSchema = mongoose.Schema({
location: {
type: String,
required: true
},
type: {
type: String,
required: true
},
name: {
type: String,
required: true
},
time: {
type: String,
required: true
},
classMembers: [classMembersSchema]
});
module.exports = mongoose.model('createClass', classSchema);
The classMembers Array is the one I mentioned that I am trying to remove members from. classMembers: [classMembersSchema].
This is the axios.delete:
deleteClassHandler = () => {
axios.delete('/api/classes/' + this.props.id + '/user/' + this.props.userId)
.then(response => {
console.log(response);
})
.catch(error => {
console.log(error);
});
}
This is the route:
router.delete('/:id/user/:userId', ClassesController.deleteUser);
This is the controller:
exports.deleteUser = (req, res) => {
GymClass.findById({
_id: req.params.id
}, 'classMembers', (err) => {
if (err) {
res.status(401).json({
message: "Error Occured!"
})
} else {
GymClass.findByIdAndDelete({
"classMembers.userId" : mongoose.Types.ObjectId(req.params.userId)
}, (err) => {
if(err) {
console.log('Keeps hitting here!');
res.status(401).json({
message: "Error Occured!"
})
} else {
res.status(200).json({
message: "Success!"
})
}
});
}
})
}
Everything works fine until it hits the console.log('Keeps hitting here!');
At the start of the function the req.params.id which is the class Id of which class we want to modify and the req.params.userId which is the user we want to remove from the Array inside the Model do have the right values but when it gets to that step it gives me the Error.
I'm thinking it could be that it is not finding this:
GymClass.findByIdAndDelete({
"classMembers.userId" : mongoose.Types.ObjectId(req.params.userId)
Since it's in an Array within the classMembers. Any idea or advice to get this to work? Many thanks.