I have located the archive pages and copied straight from them... long process but the saving is done.

I will see if deleting them works this way.

I have found a page by page deletion capability, for those wishing to do same.

Go into your DASHBOARD and select ALL POSTS...

then in that window it says BULK ACTIONS click on that and choose MOVE TO TRASH. Click on the box that will select ALL of the posts listed on that page. Select APPLY. You have to do this for each page of listing of posts, but it's quicker than individual deletions.