[BonnyCanale]

This is a customized issue. Right now, you only want 1 (or few wifi connections). And also, you want that your device should not search for those connections (from the start). I can't have an answer, as the device has to search for all the connections in a specific area available for connectivity. If you want to block all of those, you have to build a custom app, with connections that are mentioned for connectivity. And block rest of them or if get connects, the app should disconnect it easily. It is a simple app but remembers, there will be multiple issues while running the app. You will have to turn it off, in order to know available connections, in case you are moving out of city etc.