Evdoxia Renta 

Normally the way to approach is with care, because of possible homonyms, so regular maintenance can be carried out as described here:

https://docs.rws.com/796827/348614/multiterm-2021-sr2/searching-for-duplicate-terms

If you're confident that you don't have any homonyms (or you don't care) then you have two options (at least) but nothing specifically designed to just batch remove duplicates:

1. export to MultiTerm XML and XDT, create a new termbase using the XDT file so the structure of your new termbase is exactly the same, and then import the XML.  Use the option to synchronise on term... OR
2. export to Excel (Glossary Converter is best for this) and use Excel to remove your duplicates.  Then recreate your termbase from Excel, again using the Glossary Converter.

There are other tools available from companies like Kaleidoscope that can carry out more maintenance type activities, but if your termbase isn't too complex and you don't want to pay for additional software then the two methods above are probably the bread and butter solutions.

Thank you, Paul. It sounds quite complicated. I thought that there would be a way to delete all of them at once using the Advanced Search > Search for Duplicate Terms. I wonder what is the point of this search if you cannot delete them at once?

I forgot to tell you that I don't need any of the duplicates, so a merge would be ok too.

 Evdoxia Renta 

Not too complicated... I recorded a video to explain the process as I'd have to do this to take screenshots anyway and I thought this would be more helpful.