Recently I noticed that although my drive showed ~800Gb of usage, the folders within totally to around ~600Gb (and yes I was including hidden 'dot' files/folders.
After some inspection I found that there are a whole set of Disk Media Images, that appear to be related to XCode simulators. Here's an extract from the command line diskutil list command:
/dev/disk5 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +17.6 GB disk5
Physical Store disk4s1
1: APFS Volume iOS 26.2 Simulator 17.1 GB disk5s1
/dev/disk6 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +14.2 GB disk6
1: Apple_APFS Container disk7 14.2 GB disk6s1
/dev/disk7 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +14.2 GB disk7
Physical Store disk6s1
1: APFS Volume XROS 26.2 Simulator 13.8 GB disk7s1
/dev/disk8 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +17.2 GB disk8
1: Apple_APFS Container disk9 17.2 GB disk8s1
/dev/disk9 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +17.2 GB disk9
Physical Store disk8s1
1: APFS Volume iOS 26.0 Simulator 16.7 GB disk9s1
/dev/disk10 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +8.5 GB disk10
1: Apple_APFS Container disk11 8.5 GB disk10s1
/dev/disk11 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +8.5 GB disk11
Physical Store disk10s1
1: APFS Volume XROS 2.5 Simulator B... 8.2 GB disk11s1
/dev/disk12 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +18.0 GB disk12
1: Apple_APFS Container disk13 18.0 GB disk12s1
/dev/disk13 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +18.0 GB disk13
Physical Store disk12s1
1: APFS Volume XROS 2.5 Simulator 17.5 GB disk13s1
/dev/disk14 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +17.6 GB disk14
1: Apple_APFS Container disk15 17.6 GB disk14s1
/dev/disk15 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +17.6 GB disk15
Physical Store disk14s1
1: APFS Volume iOS 26.1 Simulator 17.1 GB disk15s1
/dev/disk16 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +14.1 GB disk16
1: Apple_APFS Container disk17 14.1 GB disk16s1
/dev/disk17 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +14.1 GB disk17
Physical Store disk16s1
1: APFS Volume XROS 26.1 Simulator 13.7 GB disk17s1
/dev/disk18 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +17.6 GB disk18
1: Apple_APFS Container disk19 17.6 GB disk18s1
/dev/disk19 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +17.6 GB disk19
Physical Store disk18s1
1: APFS Volume iOS 26.1 Simulator 17.1 GB disk19s1
/dev/disk20 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +9.1 GB disk20
1: Apple_APFS Container disk21 9.1 GB disk20s1
/dev/disk21 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +9.1 GB disk21
Physical Store disk20s1
1: APFS Volume iOS 18.5 Simulator B... 8.8 GB disk21s1
/dev/disk22 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +20.7 GB disk22
1: Apple_APFS Container disk23 20.7 GB disk22s1
/dev/disk23 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +20.7 GB disk23
Physical Store disk22s1
1: APFS Volume iOS 18.5 Simulator 20.2 GB disk23s1
I am unable to unmount them, either from the command line or Disk Utility. How do I go about this?