Add or delete fields to a existing termbase.

Hi,

I created a termbase and started to work on a project, now I think my termbase need to have two new termbases to add more information to the termbase. I select Project Settings -- > Language Pairs -- > All Language Pairs -- > Termbase. In the termbase window, the Settings button is disabled to change the current termbase from it. Is it possible to add new fields or delete previously created fields for an existing termbase? If yes how to do it?

Note: I don't have MultiTerm on the machine, just SDL Trados Studio Professional 2019 

Best Wishes,

Masoud