I can't remove very old stock alert items and sales orders

Hi there,

We have decided to start using inventory again. It was tried a few years ago but didn't really work.

I'm having trouble trying to remove old items from the Stock Alert tab. I have already changed/deleted all the info in the items buying tab. This is not an inventry item and if I untick the I Buy this item, it still shows up in the Stock Alert tab but now unbale to select the item as it greyed out.

I also can't go back and delete/remove the sales order related to this as it's all a few years old and the year is locked off (going back to 2006) most have a zero balance but agian I can't do anything as that year is locked off

Pleae help