The `Remove` element tool renders a remove button at a given position above the element. It accepts a few additional arguments, which can be passed as an object to the element tool constructor:

x | string | number | Use percentage strings (e.g. `'40%'`) to position the button relatively to the element width/height. A number means distance from the top-left corner of the element. Default is `0`.
y
rotate | boolean | Should the button rotate according to the element angle around the element center? Default is `false`.
offset | object | Additional offset of the button from the position defined by `x` and `y`. Default is `{ x: 0, y: 0 }`.
action | function | What should happen when the user clicks the remove button? Default:
    function(evt, linkView, toolView) {
        linkView.model.remove({ ui: true, tool: toolView.cid });
    }
markup | JSONMarkup | The markup of the button, provided in the JointJS JSON format. Default is `undefined` (no content).

Example:

    var removeButton = new joint.elementTools.Remove({
        focusOpacity: 0.5,
        rotate: true,
        // top-mid
        x: '50%',
        y: '0%',
        offset: { x: 10, y: 10 }
    });