Unable to remove Windows Boot Camp partition
The proper commands, to remove Windows and add the free space back to macOS, are given below. The commands should work unless there is a problem with APFS.

sudo  diskutil  eraseVolume  free  none  disk0s4
sudo  diskutil  eraseVolume  free  none  disk0s3
sudo  diskutil  apfs  resizeContainer  disk0s2  0


The next sequence of commands removes any Windows boot code that may exist in the hidden EFI partition. 

diskutil  mount  disk0s1
cd  /Volumes/EFI
rm  -fr  EFI/Windows
rm  -fr  EFI/Boot
cd  /
diskutil  unmount  disk0s1