Apple - Remove disk image from the disk list
hdiutil
will show information about all mounted DMGs:
hwd@hwds-iMac:~$ hdiutil info
framework : 415
driver : 10.11v415
================================================
image-path : /Users/hwd/Downloads/mountedImageOne.dmg
image-alias : /Users/hwd/Downloads/mountedImageOne.dmg
shadow-path : <none>
icon-path : /System/Library/PrivateFrameworks/DiskImages.framework /Resources/CDiskImage.icns
image-type : UDIF, nur Lesen, komprimiert (bzip2)
system-image : false
blockcount : 22528
blocksize : 512
writeable : false
autodiskmount : TRUE
removable : TRUE
image-encrypted : false
mounting user : hwd
mounting mode : <unknown>
process ID : 5376
/dev/disk2 Apple_partition_scheme
/dev/disk2s1 Apple_partition_map
/dev/disk2s2 Apple_HFS /Volumes/mountedImageOne
================================================
image-path : /Users/hwd/Downloads/mountedImageTwo.dmg
image-alias : /Users/hwd/Downloads/mountedImageTwo.dmg
shadow-path : <none>
icon-path : /System/Library/PrivateFrameworks/DiskImages.framework/Resources/CDiskImage.icns
image-type : UDIF, nur Lesen, komprimiert (zlib)
system-image : false
blockcount : 20480
blocksize : 512
writeable : false
autodiskmount : TRUE
removable : TRUE
image-encrypted : false
mounting user : hwd
mounting mode : <unknown>
process ID : 5416
/dev/disk3 GUID_partition_scheme
/dev/disk3s1 48465300-0000-AAAA-AAAA-000000000000 /Volumes/mountedImageTwo
The question is actually "How to remove...".
It can be ejected by using the device path
diskutil eject /dev/disk4
Substitute disk4
for whichever disk is offensive.
Mount them through Disk Utility and you will see them in Finder where you can just unmount them by clicking on the eject icon in the sidebar next to their names (in Finder) and they will disappear.