distroy cascade is not wotkin in Sequelize orm

i have two model create with Sequelize cli first model user_number secound model emailSign my models is 1 - user_number model

    'use strict';
     module.exports = function(sequelize, DataTypes) {
     var user_number = sequelize.define('user_number', {
     user_id: DataTypes.INTEGER,
     callRoute_id: DataTypes.INTEGER,
     password: DataTypes.STRING,
     }, {
     underscored: true,
     classMethods: {
         associate: function(models) {
            // associations can be defined here
             user_number.hasMany(models.emailSign, {
                foreignKey: 'user_number_id',
                onDelete: "CASCADE",
             });
           }
           }
        });
      return user_number;
    };

2- emailSign model

      'use strict';
      module.exports = function(sequelize, DataTypes) {
      var emailSign = sequelize.define('emailSign', {
      email: DataTypes.STRING,
      user_number_id: DataTypes.INTEGER
      }, {
         underscored: true,
         classMethods: {
             associate: function(models) {
             // associations can be defined here
             emailSign.belongsTo(models.user_number, {
             foreignKey: 'user_number_id',

           })
         }
        }
      });
      return emailSign;
          }; 

I Want distroy user_number casscade Remove emailSign my code for distroy is

User_number.distroy({where:{id : 5}}).then(function(){

resp.status(200);
) 

user_number with id 5 is Remove But emailSign dont remove I How can Remove casscade emailSign??
m

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