What would most likely work best to remove that is CCleaner, a freeware product we highly recommend. You can find links to it in our
Freeware DB. I believe the particular item to which you refer is "User Assist History" in the Advanced section under the Windows tab of the Cleaner tool.
Please note that in order to keep CCleaner free they usually offer a toolbar or some other thing you likely want to uncheck on install.