Welcome @zhuo7752
Sorry to hear you are having some problems!
For the initial file deletion, this was probably just a web browser communication hiccup. The suggestion would be to refresh the browser window (click on the Home icon) then to try again.
If that is what you already did, and the web error did not repeat, then your data should be queued for permanent deletion.
From your side, the data will now appear as a deleted dataset (or entire history) and be annotated as “purged”. Your data overview of active/deleted/purged status under User → Preferences → Storage Dashboard in the graphics will also always be current!
However, when removing larger amounts of data, the account or history quota recalculation top usage numbers will update within a day as the process completes and the disc space is actually freed up and available for reuse.
The delay can be confusing, so I am glad you asked!
And finally, this part is a bit concerning when working at the public servers. Reviewing the Acceptable Use section here may be helpful? GDPR | Terms of Service, Maybe this is already Ok?
If after a day things still look wrong, we can help more! Maybe share some screenshots? Or we could move to a private message here to share a history link? Please let us know how this goes! 