On Kitchen > Ingredients (/admin/ingredients) or Kitchen > Sub-Recipes (/admin/subrecipes):

1. Tick the checkbox on one or more rows - a Delete button (and, once you tick the Deleted Ingredients/Subrecipes filter and select disabled rows, a Restore button) appears above the list.
2. The Search box matches on ID, Name and Internal Name, and searches automatically a moment after you stop typing - there's no minimum number of characters required. Filters on the left narrow by category, meal category, By-the-Pound type and (ingredients only) custom type; Sort by offers Name A-Z/Z-A, price high/low and ID high/low.
3. Each row's edit page has a Clone icon that opens a new item pre-filled from that one.

Deleting sets the item inactive rather than erasing it - it disappears from meal/recipe pickers but can be restored the same way.