Delta between used space on disk and used space on dashboard

There is no way to clean up this disk from Storj’s data without disqualification.
The only exception is temp folder, see

What’s your allocated space in the STORAGE option of your docker run command?
You should have a reserve of 10% when you configured an allocation, for the 5.1 TiB disk it should not be more than 5TB.

From the dashboard it looks like your STORAGE=4.07TB, and 4.06TB is used, so no discrepancy here.

Please show result of this command:

df -T --si