Cannot remove bootcamp partition
This answer has been posted many times before. Why not once more. The commands are given below.

diskutil  eraseVolume  free  n  disk0s4
diskutil  cs  resizeStack  01CA9FDB-EE71-4B65-9216-2A7EB5CBA511  0


If any of the above commands fail, you can try to repair macOS volume by entering the following command.

sudo diskutil repairVolume disk0s2


If the repair command does not resolve issues, then you have the following options:


Erase the disk and reload from a time machine backup.
Backup your files, reformat the partition, reinstall the macOS, the reload your files.