Memory issues

I feel that that free space desapear from my kw88. I am constantly deleting stuff to create free space to install new faces but it seems that the memory of my kw88 is always filling up with some new datas that I cannot identify. Would that be cache ? If so, how to delete the cache ? I am scared of deleting stuff that I should not and ending up with a non working watch… Please help ! Thanks you in advance for your precious advises.