Load the file into MP3tag,
Right-click on the cover display in the tag panel,
select "Remove cover"
Press Ctrl-S to save the modification.
This deletes the selected, embedded picture from the file.
Makes a better difference between embedded picture. Hardly any player can cope with more than 1 picture and even fewer evaluate the set type. Usually, players tend to take the first embedded picture they find.
Volume control icon? As MP3tag is a tagging program I doubt that it has influence on the appearance of a player. The volume is property of the audio data that MP3tag leaves as it is.