Show which MP3 songs contain an embedded artwork/picture in metainfo? Removal?

Assume I let MP3tag scan a whole dir tree with lots of MP3 files.

How can I see which of the MP3 files contain in the meta data an artwork (=picture)?

I miss a corresponding column.

Assume I found 45 songs with embedded artwork.

I mark them all and want to strip (=remove) the artwork. How can I achieve this with MP3tag?
All remaining meta data should be kept!

Use a filter
%_covers% PRESENT
or create a column with the field %_covers%.

To remove:
select all filtered files
open the extended tags dialogue
click the red x next to the picture frame
confirm with OK.

Don't you want to save the pictures first to the file system?
Then export them with an action of the type "Export cover"

Thank you.

There is already a column named "cover".
Is it the same as a new column with field %_covers%

I don't know - you would have to check with a look at the properties of that column
right-click on the column header and open the dialogue "Columns ..." that can now be accessed via the context menu.