In the Bank Statement section of banking you can:

Track the account statement imports that have been carried out

This can be done for all accounts or separately per account if you have several bank accounts in use.
Select the account you want to track imports for in the filter, select the period and the type of import: Manual, online or all.

In this view you can also see the opening and closing balances for each import if the information is available in the account statement.

Click on the column headers if you want to sort the imports in another order.
If you work with incoming reference payments these imports can also be tracked here in the same manner as account statements are tracked.

Track individual bank statements that have been imported

Click on the import row  to go to the transaction list and check what transactions were included in this specific import.

Or click on thet the end of the row to view the transaction as an account statement as it was imported form the bank including its opening and closing balances.

Revert the import of any manual account statement import

To revert an import, you simply click on the bin icon at the end of the row.

A message informs you which transactions will be removed from Banking. If journals have been created from the account statement, you get a warning that they will be unlinked from these transactions but not deleted.

Tracking deletions

Under Reports - Activity Log, select Accounting and then Banking (Revert Bank Import). 

All deleted imports are logged here. Including Incoming reference payments imports.
Read more about the Activity log.