For changing the opacity of the element, do the following:

1. Select the element and expand the Effects tool from the right toolbar.

2. Click the Plus icon and choose the Opacity effect from the left. the opacity of the element.fw-ekA.png

3. Adjust the opacity level to get the look you want.

4. You can uncheck the Display checkbox to hide the effect. the opacity of the element2.fw-RXc.png

5. For removing the effect, click the Delete button.

6. Save the page when you're done.