Bootcamp stuck at: Please wait while boot camp assistant is removing the partitions it created
I've just encountered the same issue as you and have resolved it. 

The issue for me was caused because I am using a windows ISO that contains x86 and x64 versions which is too big for the small reserve space bootcamp sets aside for the install ISO. Get a version that is specific to what you need x64 OR x86

anyway, you need to make a backup of your mac on a hard drive, using Time Machine is fine and the easiest way. Or simple remove your critical files and set up from fresh.

REBOOT
HOLD COMMAND+R
ENTER DISK UTILITY

You need to find the master drive for the hard drive that has the issue. (you can select view all drives/volumes on the top left if you don't see it straight away.

My drive was something like "APPLE SSD0256R DRIVE" 

click ERASE and name it exactly as you see the name written before . (It should be MAC OS JOURNALED from the drop down menu too) Now click ERASE again to confirm. 

You will now have restored the drive to a single partition.

QUIT DISK UTILITY

Now proceed to use time machine to restore or reinstall Mac OS from the previous menu.

That will put you back in the state before attempting to install windows. 

P.S. I did try to use the command line options as mentioned elsewhere but they just would not work for me so this was the only way. 
Hope you get it all sorted!
_/_