Element deactivation on a list

Do you mean a Data Validation cell with the list option? No type of list allows specific items to be visible but disabled. It is possible to disallow selection of particular items with macros. The strategy is to use the Worksheet_Change event, and check to see if that cell has been changed to a disallowed value. If you, you change the value back to a default value.

If you post your file and describe in more detail I can provide more detailed information.