how to remove selected rows from grid extjs 4

Hello i have grid then i can select few or all the rows and on toolbar delete button. I can delete one row but for remove several selected rows i don't have method. Somebody can help me? Thank you.

This for delete one selected row:

Code:

listeners: {
                        click: {
                            scope: this,
                            fn: function (sm, selection) {
                                var selection = this.getView().getSelectionModel().getSelection()[0];
                                /*if (selection.length > 1) {
                                    store.removeAll(selection);
                                }*/ //This not working
                                else
                                    store.remove(selection);
                                    store.sync();
                                }
                            }
                        }

how to remove selected rows from grid extjs 4