I'd be very careful about using containment, particularly if that SSID is not reported as a rogue (i.e. connected to your wired network); it's potentially a DoS attack on your part, on a public unlicensed area of spectrum. If it's just someone else's nearby network, check how it may or may not be affecting your own setup through co-channel interference (the Wireless > RF Spectrum menu) If it's not overlapping greatly with the channels set on your AP(s) - or is only seen faintly - I'd just leave it TBH. If it is interfering significantly, maybe have a look at wider spectrum usage where you are and maybe manually set channels (and things like channel width) in your RF Profile - under Wireless > Radio Settings