Cleaning up disks from prior installs

[Will Senn]

I'm not yet entirely clear on netbsd's approach to partitioning. I have 
my T430 set to UEFI only, no CSM. I have noticed that during 
installation, sticking to GPT, I have issues with the disk provisioning 
steps that are baffling. The solution I've found to be repeatable and 
dependable is to boot into linux mint's live usb, run gdisk and zap the 
gpt and mbr partitions on the disks then the install never fails. Since 
I'm trying to dedicate the laptop to netbsd, this seems less clean than 
I'd like. I took a look around and can't find any netbsd way of zapping 
the drives that's quick and dependable, leaving no effective trace of 
whatever might have been there (not like zeroing out the whole disk). Is 
there a "delete partitions and signatures from a drive" utility that's 
on the install media that I can run before doing a clean install?

I tried dd if=/dev/zero bs=4M count=lotsofthem and the installer failed 
to create the filesystems. Maybe lotsofthem were too many and I should 
only have done some smaller number?

Thanks,

Will