Black Out Certain Portion Of The Video

I am super new to the Final Cut Pro X. I have a very simple question. I want to black out or remove a certain portion of the video without cropping that part. Below is an example image from the video:

You can see a blue text on the left top corner. I want it gone without cropping it. It should be black like the area behind it. Can somebody guide me how i can acheive that. Thanks!