how can i remove the '@' symbol in front of the names of the custom windows ?
10x

You should check the help file before asking here.

Straight from the helpfile (/help /window):

k[N] = hides the @ prefix in the window name, 0 = hide prefix, 1 = show prefix

So /window -k0 @mywindow

Note: You can use -k without a 0.

True, however I prefer giving newbies the correct syntax, even if mIRC doesn't take it as narrow with its syntax at times.

10x ...
i didn't looked in the help file cause i tought it's done by some kind of .dll...