Tipex? Cross it out 'neatly' or chuck the whole thing in the bin?
I have said to DH to put a line through it (not scribble), not to use tipex, he disagrees.
(I suspect, the reality is 'throw it in the bin' though given that i have heard of people throwing applications in the bin as the writing on the envelope was not straight and given that there are hundreds of applicants for one job)