When entering a bug into radar, I accidentally attached a screenshot to the configuration information through the "Choose file for upload" button. Realizing my mistake, I wanted to unchoose a file for that widget, but it does not appear possible. The workaround is to reset the form and start again, which is less than satisfactory.
<rdar://problem/3669167>
<rdar://problem/10056080>
*** Bug 69192 has been marked as a duplicate of this bug. ***