You’ll have to deregister them and then re-register them ensuring the fifth param of wp_register_script() is set to true
https://codex.wordpress.org/Function_Reference/wp_register_script
Note: Careful things don’t break as a result of moving scripts to the footer.
Okey like others scripts of wp core but do you know the handle of bp scripts ?
Not off the top of my head but try searching the BP codebase for wp_enqueue_script
using either your code editor or the BP GitHub repo search form:
https://github.com/buddypress/BuddyPress
That should throw up all the handles you need.
okey thanks in fact i will use the wonderfull plugin : BWP Minify 😉
https://wordpress.org/plugins/bwp-minify/