Internet Explorer has a feature called autocompletion. The AutoComplete feature saves previous entries you've made...
for Web addresses, forms and passwords on Web pages you have used in the past. When you type information in one of these fields, AutoComplete suggests possible matches from the entries you made previously if they match what you are typing currently.
You may have turned this feature off (so no one knows what you have been entering in these fields), but if you still have it on and want to remove the entries, you can do so in two ways:
Go to Tools -> Internet Options -> Content. The Autocomplete button allows you to clear all the forms and their saved entries
Or, begin typing text that matches the entry you wish to erase in the field you wish to erase the entry from. When the dropdown list of potential autocompletions appears, press the down arrow to enter the list and then press "delete" on the keyboard to delete the particular entry that you're on at the time.