The chairman of a Port Vue-based political organization said he was given an ultimatum — remove an “Impeach Obama” sign or vacate the quarters he rents in a shopping center along Washington Boulevard in the borough. Mon Valley Republican Committee chairman Brent Kovac said he did neither, so on Thursday his landlord Helen Siudyla-Totty painted over a sign that was painted on plywood posted after the political committee storefront was vandalized in October 2008. “We did that mural on the panels where our windows were,” Kovac said. Bricks and a tire were hurled through the storefront window a few weeks...