It all depends on whether your distro uses Busybox for
To point you in the right direction, run
ls -l /sbin/init.
If you get something like the following (example from OpenWRT):
~# ls -l /sbin/init
-rwxr-xr-x 1 root root 10824 Jan 31 2016 /sbin/init
init is a different application and you may be able to remove Busybox. You'll still need to replace all the command
init requires with alternatives as Busybox provides many tools required for booting successfully.
However, if you get (example from Alpine Linux):
~$ ls -l /sbin/init
lrwxrwxrwx 1 root root 12 May 3 04:49 /sbin/init -> /bin/busybox
init is provided by Busybox and you'll not be able to boot unless you can replace Busybox's
init with an alternative.
You have to consider whether you are really hardening your system by doing this as you'll end up replacing one binary with many.