[help] I can't remove some BTRFS subvolumes + bonus questions

Hello! My disk space was out of space left, so I decided to remove some snapper snapshot. snapper list listed over 360 snapshots. I removed them, and freed 50Gb of space. One of these hasn't been deleted successfully:

Cannot delete snapshot 166 since it is the next to be mounted snapshot.

it's description is writable copy of #156. How can I remove it? should I do it using btrfs subvolume delete?

here's the output of sudo btrfs subvolume list -t /:

ID      gen     top level       path
--      ---     ---------       ----
256     178487  5               timeshift-btrfs/snapshots/2023-09-18_18-25-33/@
257     341688  5               @home
258     341680  5               @cache
259     341688  5               @log
260     26      256             timeshift-btrfs/snapshots/2023-09-18_18-25-33/@/var/lib/portables
261     27      256             timeshift-btrfs/snapshots/2023-09-18_18-25-33/@/var/lib/machines
708     341688  5               @
710     341680  708             .snapshots
2781    178991  5               timeshift-btrfs/snapshots/2024-05-07_12-20-43/@
2968    326034  710             .snapshots/166/snapshot
2969    341679  710             .snapshots/167/snapshot

all those timeshift subvolumes are there because before snapper, I used to use timeshift. I tried to remove them:

sudo btrfs subvolume delete timeshift-btrfs/snapshots/2023-09-18_18-25-33/@/var/lib/machines    
ERROR: Could not statfs: No such file or directory

If I understand correctly, it means that I should give an actual "system" path instead of the path in the table, but I don't understand which path

thanks in advance to everyone!