It is not possible to unset { -brand-short-name } as the default client within { -brand-short-name }. To make another application the default you must use its 'Set as default' dialog.
Man tikirel ta nib'an chi ri { -brand-short-name } nuya' kan rub'anikil achi'el winaqil k'o wi pa { -brand-short-name }. Richin chi jun chik chokoy nok ri kan k'o wi, tawokisaj 'Tijikib'äx achi'el ri k'o' tzijonem.