Circle CI does not allow deletion of containers:

Cannot destroy container
6f30ab3de4f445d4fe47059d68d9798d40f5f66b9a1120dcfd130c0cab378cb5: Driver
btrfs failed to remove root filesystem
6f30ab3de4f445d4fe47059d68d9798d40f5f66b9a1120dcfd130c0cab378cb5: Failed
to destroy btrfs snapshot: operation not permitted