I have the same question but as a work around you could create a category called "obsolete terms" for example, and that category would contain all the older unusable terms. Basically create a revision of the term and change its category to the "obsolete terms" one.
Yes. With Informatica 10.X, it is possible to delete the Business Glossary.
NOTE: Delete a glossary to permanently delete all categories, policies, and business terms in the glossary.
In case you want to delete only a few 'published' terms from the glossary, you wont be able to delete the same using Analyst Service. This is as per product design but you can give a shot at it by following the steps below:
1. Export the glossary using Analyst
2. Remove / Delete the glossary from the MRS using Analyst service
3. Take a back up of the exported glossary ( i.e. take a backup of the Excel Sheet )
4. Open the exported glossary and remove the rows containing the terms that you want to remove
5. Import the Glossary back to the MRS using Analyst
Maybe you can try this out first with a sample glossary?
Hope this helps!