Restore disk to a single macOS partition - reclaiming unallocated space left from Win

Now, with all other partitions deleted, the space is freed up and Disk Utility now recognizing the entire SSD.

However, notice that the "Free Space" is grayed out, preventing any modifications to it.

Your next recommended step was to merge the Free Space back into macOS.

diskutil apfs resizeContainer disk1 0g

Thanks for your assistance. Hope this helps.

/~ $: diskutil list

/dev/disk0 (internal, physical):

  #:            TYPE NAME          SIZE    IDENTIFIER

  0:   GUID_partition_scheme            *1.9 TB   disk0

  1:            EFI EFI           209.7 MB  disk0s1

  2:         Apple_APFS Container disk1     549.9 GB  disk0s2

  3:    Microsoft Basic Data Data HD         820.6 GB  disk0s3

  4:            EFI NO NAME         104.9 MB  disk0s4

/dev/disk1 (synthesized):

  #:            TYPE NAME          SIZE    IDENTIFIER

  0:   APFS Container Scheme -           +549.9 GB  disk1

                 Physical Store disk0s2

  1:        APFS Volume Mac HD - Data      194.9 GB  disk1s1

  2:        APFS Volume Preboot         81.6 MB  disk1s2

  3:        APFS Volume Recovery        528.9 MB  disk1s3

  4:        APFS Volume VM           1.1 GB   disk1s4

  5:        APFS Volume Mac HD         11.2 GB  disk1s5

I am learning this fact about OWC SSDs, but up 'til now I think it is more a configuration/format/partition issue. At the end of the day, I can always reformat the SSD and restore from Time Machine backups, but my hope is to outsmart the brute "reformat and reload" advice so often given by "genius bars" and Microsoft "experts". It's a challenge rooted in my long relationship with personal computer development. I sense you can appreciate this. And, again, I appreciate your efforts in this quest.

Thanks for your assistance. I've erased the errand volume - disk0s4. But when I attempt the next step, to run BC Assistant, it only offers me the option of installing windows, not removing it.

I sincerely appreciate your efforts at solving this problem. Thank you very much.

So, "diskutil apfs resizeContainer disk1 0g" whirred and chugged for a few minutes, putting everything back together.

and after a couple of hiccups, finished successfully.

Loner T - you did it. Spot on!!

Because I think this is a more common problem than just my individual case, I will try and detail it for the benefit of others. Please annotate as you feel appropriate. And thank you so much for taking the time to help me.

So, by this point, we have deleted an unnamed partition using diskutil. That did not make the unallocated space appear in either diskutil or Disk Utility.

Your next step was to suggest I delete the remaining partition, leaving only the Mac partition. This was a 850 GB partition formated exFat which I usually create to store data accessible by both OS and Win - "Data HD".