Removal of a Last Reconcile Date

[Po Mario]

In the main screen of GnuCash (the Accounts tab) I use the column "Last
Reconcile Date" to keep track of the last time I checked the correctness of
all my Assets. Recently I did something by mistake, which was reconciling
an Expenses Account. Now, there is a date in the "Last Reconcile Date"
column being shown. I personally do not reconcile Expenses and that date
confuses me when I visually scan the Accounts tab. I want
the reconcile date removed for a given account. Question: how do I remove
the date under the Last Reconcile Date column for a given account?
Many thanks,
Mario Po