in Numbers, how can I delete all the suggested auto fill items that come up when I type the first letter of what I want to enter

Numbers->Preferences

Uncheck "show suggestions when editing table cells"

The list it shows is built from the contents of the cells in the column.

It does delete them in the sense that they no longer appear when you start typing. They are, in effect, deleted. The original poster did not ask about how to edit the list, which is an entirely different question (and not possible).

The list is built dynamically from the contents in the column. Every entry in the column is on the list. If you want one to not be on the list, delete every instance of it from the column and it will no longer appear on the list. There is not a separate list you can edit.

If you want a short (up to 250 items I think) menu of allowable entries to pop up and want to prevent anything other than those to be entered, use a pop up menu.

Turning them off dos'nt delete them I want to edit them

where are the suggested comments stored