Merging a partitioned disk to Macintosh HD

After running BootCamp assistant i had created partition for windows, but somehow it got corrupted and it is not reverting back to original partition.

Now from disk utility i can see my internal disk as

i want to merge "Untitled" disk to Machintosh HD.

Below are some more information:

Command : diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *121.3 GB
disk0

1: EFI EFI 209.7 MB
disk0s1

2: Apple_APFS Container disk1 86.0 GB disk0s2

3: Microsoft Basic Data BOOTCAMP 8.0 GB disk0s3

4: Apple_HFS Untitled 27.0 GB disk0s4

/dev/disk1 (synthesized):

#: TYPE NAME SIZE IDENTIFIER

0: APFS Container Scheme - +86.0 GB disk1

Physical Store disk0s2

1: APFS Volume Macintosh HD 71.4 GB disk1s1

2: APFS Volume Preboot 19.8 MB disk1s2

3: APFS Volume Recovery 509.8 MB
disk1s3

4: APFS Volume VM 2.1 GB disk1s4

Command: diskutil apfs list

APFS Container (1 found)

|

+-- Container disk1 9449D134-E5B3-4AD5-AF99-C69F23E2C158

====================================================

APFS Container Reference: disk1

Capacity Ceiling (Size): 86001037312 B (86.0 GB)

Capacity In Use By Volumes:
74189864960 B (74.2 GB) (86.3% used)

Capacity Available: 11811172352 B (11.8 GB) (13.7% free)

|

+-< Physical Store disk0s2 9308D1BE-470B-466F-935E-FE689CF36CE2

|
-----------------------------------------------------------

|
APFS Physical Store Disk:
disk0s2

|
Size: 86001037312 B (86.0 GB)

|

+-> Volume disk1s1 802F582E-D929-331C-A072-EF965B5B018D

|
---------------------------------------------------

|
APFS Volume Disk (Role):
disk1s1 (No specific role)

|
Name: Macintosh HD (Case-insensitive)

|
Mount Point: /

|
Capacity Consumed: 71389597696 B (71.4 GB)

|
FileVault: No

|

+-> Volume disk1s2 3821AE54-55D7-4251-92A6-E680A6C3CD00

|
---------------------------------------------------

|
APFS Volume Disk (Role):
disk1s2 (Preboot)

|
Name: Preboot (Case-insensitive)

|
Mount Point: Not Mounted

|
Capacity Consumed: 19804160 B (19.8 MB)

|
FileVault: No

|

+-> Volume disk1s3 8C74FD91-E27E-4A5F-9F3D-4DE6DB3B1A6E

|
---------------------------------------------------

|
APFS Volume Disk (Role):
disk1s3 (Recovery)

|
Name: Recovery (Case-insensitive)

|
Mount Point: Not Mounted

|
Capacity Consumed: 509820928 B (509.8 MB)

|
FileVault: No

|

+-> Volume disk1s4 78587538-60C5-4692-ADA3-0D01814729DF

---------------------------------------------------

APFS Volume Disk (Role):
disk1s4 (VM)

Name: VM (Case-insensitive)

Mount Point: /private/var/vm

Capacity Consumed: 2147520512 B (2.1 GB)

FileVault: No

Please suggest some ideas other than restoring MAS OS to factory reset.