Removing bootsector from USB

[spleenharvester]

Basically, I've been a moron. In Windows RE I accidentally wrote a bootsector to my multiboot stick, and now any attempts to boot from it just result in "BOOTMGR is missing, press any key to restart".

All the ISOs and files are still on there and it took forever to make (with YUMI, syslinux/GRUB). Is there any way to recover it without a wholesale diskpart clean?

Thanks

 

[spleenharvester]

Supposedly removing libcom32.c32 and ldlinux.sys from /multiboot/ will force YUMI to reinstall syslinux but I tried something else beforehand that mucked it up completely, so I am just going to rebuild the stick.