dock icons can't be removed

mvgallo wrote:

All of a sudden today two icons appeared on my dock and can't be removed. Firefox appeared on my dock even though it is not installed and can't be removed. The same applies to Apple Mail which is installed but never before been on my dock. I don't use it. I have a 2017 MacBook Pro running Big Sur 11.1. Firefox icon 'option' when right clicked shows nothing, and mail icon does not have 'remove from dock'. My dock is now so full the icons are tiny! How can I remove these icons and why did they suddenly appear? I tried all recommendations such as clicking icon and float over desktop, dragging it to the trash etc. to no avail.

Many thanks for any help!

Is the Firefox.app in your Application folder— i do not see how it would magically appear if you did not install it.

Typically if you click and DO NOT hold for a bit — just click and drag with the mouse held down—you can drag off the dock to the Desktop, then let go.

Use the Dock on Mac - Apple Support

Add, Remove or Rearrange Items On Your Mac's Dock ...