Part of Apple SSD not accessible after failed bootcamp attempt
All the partitions after disk0s2 can be returned to free space. The commands to do so are given below. 

sudo diskutil eraseVolume free none disk0s8
sudo diskutil eraseVolume free none disk0s7
sudo diskutil eraseVolume free none disk0s6
sudo diskutil eraseVolume free none disk0s5
sudo diskutil eraseVolume free none disk0s4
sudo diskutil eraseVolume free none disk0s3


Next, the following command adds the free space to the APFS container in the disk0s2 partition.

sudo diskutil apfs resizeContainer disk0s2 0