Psychtoolbox>Screen.{mex*} subfunction

Close an onscreen or offscreen window or a texture. If the optional
windowOrTextureIndex isn’t provided, then all textures and offscreen windows are
closed/deleted while regular onscreen windows are left open. If you want to
close a subset of your offscreen windows or textures, but not all of them you
can also pass in a vector of texture/offscreen window handles and all handles in
the vector will be closed.

###See also: OpenWindow, OpenOffscreenWindow