If you want to hide the panel try this:
reset(Panel,SHOW);
This instruction doesn't remove the panel just hides that.
You can show it again, when it needs.
I propose modify your code:
bmap Angler_tga = <Angler.tga>;
sound Angler_snd = <Anglerspricht.wav>;
PANEL* pan_Angler; // <------- INSERT THIS LINE
.....
// ------ replace your code with this ------
// -----------------------------------------
pan_Angler=pan_create("bmap = Angler_tga; pos_x = 0; pos_y = 0; flags = overlay, visible;", 10); // layer = 10
So you can use the reset(Panel,SHOW); anytime.