Go to the bulk update/replace/delete tool. The former Bulk update tool in TANE.
In the space on the right, put in the asset you want to delete.
Set the percentage. It's at 20%, but set it higher or lower.
Press the begin button (I think it's called that).
The process isn't too bad, but here's a warning for something I discovered the very hard and drastic way.
If you decide to replace assets later, ensure you've unchecked the delete assets box! I ended up deleting most of my pine and spruce trees from a route and the backups I have are too old, shame on me, to go back and undo what I did. I've been busy repopulating my higher elevations with pines a small forest at a time.