Why do I get a ‘Remote Management’ step when installing High Sierra?
This Mac has been enrolled under Device Enrollment. Upon connecting to Apple, the device has received instructions to be managed by IBM.

This cannot be bypassed. You should contact the seller.

Mobile Device Management ‘locks’ enforced by Device Enrollment are enforced by Apple’s severs and are based on hardware identification, so cannot be removed by macOS reinstallation ― they’re defined to be enforced as soon as the Mac is unboxed for the very first time prior to any manual configuration.

About Device Enrollment