remove heart on firefox icon in taskbar

This is indicator of your profile. I guess it shows up when you have two or more profiles.

See also https://support.mozilla.org/en-US/kb/profile-management

I had indeed created a second profile accidentally, but deleted it, and the stupid heart is still there. I can change the icon to something other than a heart in the profile managment/edit, but there is no "none" that I can add to get rid of it, having only one profile. any other suggestions?