Deleting one of several mortgage interest deductions makes the itemized deductions go up! How could paying less interest possibly make total itemized deductions go up? This is a bug in the Turbo Tax software. It seems you have not thought of the case of more than 1-2 entries in this area.
Based on reading another bug report, we ended up adding up all mortgage interest documents (1098) as if they were a single one and entering that. Although the total interest paid may be correct, the rest of the information like dates and names of lenders cannot be entered accurately when doing this.
This issue should be fixed in TurboTax!