It's vital that all your transactions be entered correctly for your books to be well balanced. QuickBooks Online is a great tool able to keep track of various accounts so you can organize the financials of your business. I can provide some information about this account.
The Reconciliation discrepancies account is one that can't be deleted, as it's one of the accounts categorized as a Default account. This information and a list of other default accounts can be found in the linked article.
If you have any other questions, feel free to reach out here.