No Amiga here so from memory:
Select SYS:Tools/hdtoolbox
Icon Menu/Information
scsi_device_name = uaehf.device
run hdtoolbox
Change drive type
Read configuration
OK
OK
Partition drive
Select the second partition
Delete the second partition
Resize the remaining partition
OK
Exit
The system will reboot
Select the icon "not dos"
Icon Menu/Format Disk
Quick format.
That should do the job.
