JOOMLA : how to remove GNU/GPL Licence?

You can remove by following these steps :
1 . Go to the language folder
2. open en-GB.mod_footer.ini file

replace the text as below for footer_line1 and footer_line2

FOOTER_LINE1=Copyright © %date% %sitename%. All Rights Reserved.
FOOTER_LINE2=

note : keep "FOOTER_LINE2=" as blank