Anglular gives access denied to mymodal.html

I think problem is in your controller function: reply is not defined, i suppose. If you will open console, i think you will see something like this:

Error: [$injector:unpr] Unknown provider: replyProvider <- reply

If you want to inject something into your controller, you can write some service.

BTW, if you are going to use some minificator you will see errors, because when you define controller by this way and minificate your code - your injections will be minificated too.

Better way is to do something like this:

var app = angular.module('app', ['ui.bootstrap']);
app.controller('MyCtrl', ['$scope', '$modal', function ($scope, $modal) {
  $scope.removeComment = function (reply) {
    var myModalInstance = $modal.open({
      scope: $scope,
      templateUrl: 'mymodal.html',
      controller: 'modalController',
      ...
      });
    };
/* SOME CODE HERE */
}]);

and

app.controller('modalController', ['$scope', '$modalInstance', function ($scope, $modalInstance) {
  /* SOME LOGIC HERE */
}]);