When a toolbar bugs you with annoying installation or pop-up windows it means that there is something wrong with the actual toolbar. If it's forcing you to download something, most likely it is malware that tries to spread using this method which in this case you should disable automatically from the browser's add-ons or extensions. Also, if you know that the toolbar is legit, you can go into settings and customize it the way you want.
Another possibility is to go to Start > Run > type msconfig and press Enter. Navigate to Startup tab and locate the toolbar's entry name and uncheck it.