markmwest
It belongs to the footer block in template, you can edit file: /templates/ja_company/html/mod_footer/default.php
With Joomla text, it's defined in this language file: /language/en-GB/mod_footer.ini 🇦
MOD_FOOTER_LINE2="<a href=\"https://www.joomla.org\">Joomla!</a> is Free Software released under the <a href=\"https://www.gnu.org/licenses/gpl-2.0.html\">GNU General Public License.</a>"
you can override this language constant: MOD_FOOTER_LINE2 (check out this docs for how to override languages: https://docs.joomla.org/Help4.x:Languages:_Overrides )