To deter unwanted pigeons, stop feeding them as the first step, causing them to leave on their own. It is also important to take away any flat surfaces that the pigeons could potentially use for nesting.
Pigeons get plenty of food elsewhere, so they don’t need to be fed. Not only should they not be fed purposely, but try to avoid unintentional feeding, such as leaving lids off garbage cans. Throw leftovers away in a trash can with a lid on tight, and sweep the floors outside to get rid of crumbs. To prevent nesting and roosting, deter the pigeons with bird wires on rooftops and ledges, and by using netting for larger areas.