I was having the same issue, trying to compare last 2 months. I think I found a way to eliminate the total column from the report. The trick is to set up the dates for only the current period, (in my case - month). In Customize Report window check Previous Period and pick the format of the change ($ or %). Make sure your Display-Columns-by field is set to the time period you are working with (in my case - Month).
As a result, I got 3 columns - current month, previous month, and Change.
