Depending on the browser you are using, Mario Forever Toolbar can be uninstalled in different ways.
When using Internet Explorer, this toolbar can be removed by choosing Start from your Taskbar, then Control Panel and Add or Remove Programs. Choose the toolbar from the given list, hit Remove and follow the onscreen instructions.
If you are using Mozilla Firefox, Mario Forever Toolbar will be installed as an add-on for your browser. So, in order to remove it, choose the Tools section from Mozilla's menu, enter the Add-ons section, go to Add-ons Manager and, after finding the toolbar in the list, hit Remove.
For Google Chrome, click on the Customize and Control Google Chrome section of your browser and hit Options. By accessing the Extensions tab, a list of add-ons will be generated and you will be able to manage them. Choose the Remove button for Mario Forever Toolbar.