What to do with the kippah after use

Is it permissible to throw a kippah in the trash, or must it be stored?

After using a kippah, it is permissible to throw it in the trash, and there is no pious practice to store it.

The Gemara in Tractate Megillah, page 26, states: "Our Rabbis taught: Objects used for a mitzvah can be discarded, but objects used for holiness must be stored. These are objects used for a mitzvah: sukkah, lulav, shofar, tzitzit. And these are objects used for holiness: book covers, tefillin, and mezuzot, the case of a Torah scroll, the case of tefillin, and their straps." This is also ruled in the Shulchan Aruch, Orach Chaim, siman 154, that objects used for a mitzvah must be stored. In Orach Chaim, siman 21, it is ruled that objects used for a mitzvah can be discarded, and the Rema added that even for objects used for a mitzvah, one who is stringent to store them will be blessed. And although the kippah, according to the opinion of the Taz, is obligatory to wear because "and do not walk in their statutes," nevertheless, the kippah is not the essence of the mitzvah, but rather prevents the transgression of a prohibition, and therefore is not considered an object used for a mitzvah.