How to disable code completion.
Go to Tools | Options | Editor | Code Completion and un-check "Auto list members" (v5.2 and prior) or "Auto pop-up after" (v5.5 and newer). This will disable the popup lists for objects.
Auto Replace is slightly different from Code Completion but is a sort of auto complete feature that assists with writing code in the Editor. If you wish to disable this option too you will need to manually remove the listed key terms since the is no disable/enable toggle button. There are 3 lists with terms by default. Rotate between the list by using the drop down for "Language". Select the term and right click | Delete for each.