Dual boot with Linux and Windows 10
Whatever is the boot partition, be it BIOS or UEFI, the boot partition is one and only one. After booting from it, the boot software will evoke the bootloader for the chosen operating system from its installed disk.
Note that a UEFI computer does not need Grub to be installed, as the multi-boot is done by the firmware, using the EFI partition.
So the answer is that only the non-boot disk can be removed.