How to delete memory of used termbases in MultiTerm & STudio 2015

Dear helpers, On my 2nd PC, I cannot add any terms to one of my termbases either in MultiTerm or in Trados 2015 whereas on my first identical PC this works like a charm. As no one knew of any workaround or solution I uninstalled both programmes (and even SDL files under "Roaming" and "Local") and reinstalled these two. When I reopened Studio 2015 it immediately retrieved my projects previously listed in the project list. So it seems that the entire memory of Studio has not been crushed, and thus the same error "MultiTerm is unable to add this entry" appears each time I click on "Save" either in MultiTerm or in Studio ("Add new term"). Is there a possibility to delete MultiTerm's (and perhaps Studio's) memory? For testing reasons, I installed the latest versions (which I also have on both stand-alone PCs) on my laptop, and both programmes were able to add terms to the sullen termbase.  I'm really at a loss and don't know why just one PC refuses to accept new terms. So how to delete all reminiscences these two programmes might have of any previous access to this termbase, so I can establish a new link from scratch? Thank you in advance for any advice you might think of.

Wolfgang HULLMANN