Melissas-MacBook-Pro:~ estralitasky$ diskutil eraseVolume jhfs+ BC2 disk0s4
Started erase on disk0s4
Unmounting disk
Error: -69874: Couldn't modify partition map
Melissas-MacBook-Pro:~ estralitasky$ diskutil mergePartitions jhfs+ BCMP disk0s3 disk0s4
Could not find disk for disk0s4
Melissas-MacBook-Pro:~ estralitasky$ diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 440.0 GB disk0s2
3: Apple_HFS BC1 59.4 GB disk0s3
/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +440.0 GB disk1
Physical Store disk0s2
1: APFS Volume Macintosh HD 351.6 GB disk1s1
2: APFS Volume Preboot 21.9 MB disk1s2
3: APFS Volume Recovery 519.5 MB disk1s3
4: APFS Volume VM 2.1 GB disk1s4