By default, there is the device name and resolutions, and icons for Rotate, Refresh, Screenshot, and the 3-dot menu icon for device settings above every device. This is called the Device header.
You can see choose to see more of these icons if you use them frequently, or less of them in case you think it adds to the clutter.
To change how many icons you see in the device header, open the Device Config popup towards the right of the toolbar. Here, you will find the relevant options in the Header section.
Here's what each option means:
You can also turn off the device header entirely by using the toggle next to the Header entry.
If you wish to disable the device dimensions instead, open the Device Config popup again, and click the toggle to the right of the Dimensions entry.