Picard can download and replace cover art, if that option is enabled. But there’s no option to just remove the existing cover art from the file? I’m currently using WACUP/WinAmp to manually remove cover art from files. Can Picard do that too somehow? Or maybe there exists a better method to strip cover art?
Removing cover art is unfortunately not yet implemented. There is a open ticket for this feature.
There is one way to get rid of embedded cover art with Picard, but it can have side effects: If you enable “clear existing tags” without enabling “keep cover art” than Picard will, when saving files, remove all tags (including embedded artwork) completely and and then write the new data.
The side effect is that this might remove other existing tags not filled by Picard. If the tags can be read by Picard you can add these tags as “preserved tags”, so Picard will keep the original values even if it clears the tags. But depending on the format the metadata might contain additional data Picard cannot read and hence not preserve.