Delete unused / combine duplicates in single/multiple select fields

I’d love to see an option that scoops out which items of a list are not in use (anymore) and enables me to delete all these options from the list in one click.

I’d also like to be able to combine values in the single & multiple select fields. Especially when you have accidentally added a bunch of records and made a typo in the field, which will then have caused a new option to be created. Ideally I’d open up the Customize field type screen, select two or more values and hit a button ‘combine’.

I’ve been using the programs to catalogue my books & dvds for years and they have this option available, it’s an option that I highly appreciate and would love to see here, too!