Wait until you would have all used-space-filewalker finished for all trusted satellites and you have removed the data of untrusted satellites using this guide: How To Forget Untrusted Satellites
You may track the used-space filewalker progress by logs (could be not possible, if you didn’t redirect logs to the file, because by default docker handles 5 logs by 20MiB each, and 100MiB is too small amount to track the used-space filewalker, because it could take a week or more). If you redirected logs to the file, then you may track it:
grep "\sused-space" /mnt/x/storagenode2/storagenode.log | grep -E "started|completed" | tail
The other way is to use a debug port and the method /mon/ps.