I have activate the widget in my WordPress site in admin panel, but on the front page I don't want to display it. Is this possible?
It sounds like you have a widget that you want to display on every page but the front page? If so, the Widget Logic plugin will do what you're after. You should be able to use the logic
Yes, you can enable or disable widgets from the Appearance menu of the Wordpress admin panel. Goto Appearance->Widgets then you can drag the widget from the "Sidebar Widgets" area to either the "Available Widgets" or "Inactive Widgets" boxes. If you use the "Inactive Widgets" option, Wordpress will save your widgets settings for later use.