Start by calling up the Registry Editor. To do so, go to Start/Run, then type "regedit" without the quotes in the "Open" box. Click on OK.

Make sure that the topmost entry --My Computer -- in the left-hand pane is highlighted.
Go to the Edit menu and click on Find.
In the window that opens, see to it that the boxes to the left of Keys, Values, Data are all checked.
In the Find What box in the same window, enter the name of the program, device or item you want to find, then click on the Find button.

When an entry is found, put your cursor on the specific item you want to delete -- it will be highlighted -- and right-click on the entry. From the pop-up menu choose Delete.

Return to Edit and choose Find Next and delete the next reference. Repeat the process until no more references to your search term are found.

However, one reason the Registry is so complicated is that there can be multiple references to any program, peripheral or device.

So, you will have to do additional searches, this time looking for other references to the program or device. You do so by looking for the manufacturer's name as well.

Example, if you want to remove references to McAfee's AntiVirus, you would search, separately, for both terms.
And be careful.