Deleting bootcamp

In your specific case, given the current state, try

• Step 1

diskutil eraseVolume jhfs+ BC1 disk0s3

diskutil eraseVolume jhfs+ BC2 disk0s4

diskutil mergePartitions jhfs+ BCMP disk0s3 disk0s4

diskutil list

• Step 2

If you see only disk0s3 as the last entry under disk0, then run

diskutil eraseVolume fat32 BOOTCAMP disk0s3

and retry removing the partition using BC Assistant only.

Your previous attempt(s) at Bootcamp/Windows installation failed. It should not take more than a few minutes to remove the partitions to clean them up and be ready for the next attempt.

If you are on Mojave, you may have some APFS corruption, which is causing problems.

If the 'rollback' does not complete in the next few minutes, press Command+Option+Esc and Force Quit BC Assistant. We can manually clean up.

Post the output of

diskutil list

for the manual cleanup steps.

Can you post the output of

diskutil list

from macOS Terminal?

Excellent!