OK, solved it using this info: Is there a quick way to delete old tiddlers?(I copied from main TW)
Make a tiddler called Purge1 with this content (making sure to adapt the filter on the Make Purge2 List button):
- Edit this Purge1 tiddler and set the filter
- Click this “Make Purge2 List” button
- Edit the [[Purge2]] tiddler and verify the list is correct
- Click the “Delete Purge2 List” button
<$button>Make Purge2 List
<$action-listops $tiddler=“Purge2” $filter="[search[foo]!is[system]!search[Purge]]-twhelp"/>
</$button>
<$button>Delete Purge2 List
<$action-deletetiddler $filter="[list[Purge2]]"/>
</$button>
In this example all tiddlers containing the word foo (except the word Purge so this tiddler isn’t also deleted) are listed into Purge2 and can then be deleted.