So I just installed Tumbleweed with btrfs and somewhere kind of messed up, so now my installs uses Grub as a bootloader. However since I have a Setup with another installtion that uses systemdboot and I never had a single problem with systemd I would like to move my installation away from Grub to systemdboot. However, I have no Idea how to do that and couldnt find a somewhat straightforward guide for this. Additionally systemd did not update its boot tables, so it still tries to boot into the OS that was installed on my drive, that now contains suse, previously. I would also like advise in how I can remove that entry.
@Aipathon Hi and welcome to the Forum 
New installs of Tumbleweed use grub-bls which is not dual/multiboot, one needs to use the BIOS boot menu to select alternative operating systems…
I did switch Leap 16.0 from grub-efi to systemd-boot as a test https://forums.opensuse.org/t/leap-16-slow-to-open-full-disk-encryption-tpm-2-0/188836/15
If it’s a fresh install, probably quicker to re-install and at the final install page review the bootloader and select systemd-boot?