Microsoft has mentioned that Windows Phone 7 devices have a kill switch option for removing dangerous applications from both the Marketplace as well as from a users Windows Phone 7 handset if they have to.
PC Pro explains exactly how they can deal with the situation if it arises. The first and the easiest option for Microsoft is to remove the application directly from the marketplace. This way, users will no longer see the application online if they went searching for it, but this wouldn't remove the problem application from a users handset if they had already downloaded it.
Microsoft's Todd Biggs, who is the director of product management went on to say that if an application is dangerous they could initiate a kill switch style action. In this move, when a users handset does a check for marketplace updates, which Windows Phone 7 automatically does, if the application is bad enough, Microsoft can remove it directly from your handset.
Biggs however did say that Microsoft performs stringent testing and checks on applications before they enter the marketplace, to ensure that rogue apps do not get through.
Microsoft is not the only company in the mobile industry with the ability to remove dangerous applications from phones. Earlier this year Google confirmed that they could remotely delete Android applications if they need to.