To make an item inactive, open the inventory item screen and check the box, to the far-right, Item is inactive. When you open the item List, there is an Is Active filter for you to separate the items. Once an item is inactive, you can no longer use it until you make the item active again. All transactions will remain for the item.
To make multiple items inactive at once, use the Item Inventory import template. It is located in the C:\Program Files\NumberCruncher\All Orders\Import\ItemInventory.xls. List your items in the Column A, Item Full Name, and in Column D, IsActive, enter False. When you import those items, they will become inactive in bot All Orders and Quickbooks. Make sure that your QB file is open.
Here is a video tutorial on Exporting reports from AO to Excel. Use this to export your item list to Excel:
Next copy and paste your item list to the import template. Here is the video tutorial on importing lists into AO: