If you can use a filter to get the list the tiddlers you want to delete, then you can use the delete button (“trash can”) in $:/AdvancedSearch > Filters tab to bulk delete all matching tiddlers.
If you want to exclude a few specific tiddlers from your filtered list, you can add -[[NameOfTiddler]] to the filter.
Alternatively, if you install
https://tiddlytools.com/#TiddlyTools%2FSearch%2FFilters, you can enter your desired filter and press the delete tiddlers button (“trash can” - upper right of the TiddlyTools/Search/Filters interface). This will then display a modal dialog with a checkboxes for all matching tiddler titles. You can then clear the checkmarks for any tiddlers you want to keep, and then press the “delete” button to delete the rest of the listed tiddlers.
enjoy,
-e