user = {
    "userId" : "myId",
    "connections":
    [{
        "dateConnectedUnix": 1334567891,
        "isActive": true
    }, {
        "dateConnectedUnix": 1334567893,
        "isActive": false
    }]
}

user = {
    "userId" : "myId",
    "connections":
    [{
        "dateConnectedUnix": 1334567893,
        "isActive": false
    }]
}

userAccounts.update({'connections.isActive': false },
                    {$pull: { 'connections.isActive':false }},
                    function (err,val) {
                        console.log(val)
                    });

userAccounts.update({'connections._id': '1234-someId-6789' },
                    {$pull: { 'connections._id': '1234-someId-6789' }},
                    function (err,val) {
                        console.log(val)
                    });

userAccounts.update(
      { userId: usr.userId },
      { $pull: { connections : { _id : connId } } },
      { safe: true },
      function removeConnectionsCB(err, obj) {
          ...
      });

var ObjectId = require('mongoose').Types.ObjectId;

userAccounts.update({'connections._id': new ObjectId('1234-someId-6789') },
                {$pull: { 'connections._id': new ObjectId('1234-someId-6789') }},
                function (err,val) {
                    console.log(val)
                });

Customer.findOneAndUpdate(query, {$pull: {address: addressId}}, function(err, data){
        if(err) {
          return res.status(500).json({'error' : 'error in deleting address'});
        }

        res.json(data);

      });

const removeTansactionFromUser = (userId, connectionId) => {
    return User.findByIdAndUpdate(userId, { $pull: { "connections": connectionId} }, {'new': true} );
};