How to delete storage in 'Other Volumes in Container'?
I had this same problem too, I solved by this step

diskutil list

    /dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         121.0 GB   disk0s2

   /dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +121.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume 未命名 - 数据           93.1 GB    disk1s1
   2:                APFS Volume Preboot                 82.4 MB    disk1s2
   3:                APFS Volume Recovery                528.3 MB   disk1s3
   4:                APFS Volume VM                      1.1 GB     disk1s4
   5:                APFS Volume mac - Data              13.7 GB    disk1s5
   6:                APFS Volume mac                     11.3 GB    disk1s6
   7:                APFS Volume Untitled                487.4 KB   disk1s7

   /dev/disk2 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            Fonedog-PowerMyma-1... +162.5 MB   disk2

   /dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            OmniDiskSweeper        +25.2 MB    disk3


then delete the 93.1 GB    disk1s1

diskutil eraseVolume APFS Blank /dev/disk1s1


all done