If you want to clean up your media library, you can delete image or video assets that you no longer need. Note that assets used in any of your account's programs cannot be deleted. You'll need to first delete the asset from the program before you can delete it from the media library.
To delete a media asset from your media library:
In any of your programs, select any media asset inside its placeholder.
In the right pane, click the asset thumbnail.
Your media library—with all its content—is displayed.
Locate the media asset that you want to delete.
Hover over the asset thumbnail and then click the three dots in the upper corner.
If you're sure that you want to delete the asset, click Delete.
The media asset is deleted from the media library.
If the media asset is being used by any of the programs in your account, the message below is displayed. You'll need to first delete the asset from the program if you want to delete the asset from the media library.