ok, heres the deal.
i have used a texture somewhere in my map which isnt supposed to be in there (it shows up as used in the texture list).
but i do not want it in my map, how do i find it?
i dont know on what brush it is…
is there a way?
i really want to get rid of it 
How to find the Place of a certain Texture?
eventually i found out by myself.
opened the map with a texteditor, searched for the texturename, found it and then searched for the brush in radiant.
just wondering if theres a way within radiant. 
There is - look at Loffys reply at the bottom :
http://www.splashdamage.com/forums/viewtopic.php?p=167271&highlight=#167271
You can also use the “find/replace” funtion in radiant. Very convenient when you want to replace one kind of texture with another.
where?
i know that i can search for brushes, but how do i search for textures used? (1.4)

Place your cursor above the “find” textbar, and then click on the texture you wish to replace, it will automatically fill out the bar.
Then place your cursor above the “replace” textbar and find the texture you wish to replace the first one. Press “apply”.
Beware that this will replace ALL instances of said texture, unless you tick the “selected brushes only” box.