In the verb おさめる, the kanji 収 represents only the おさ part of the word. The める part is called おくりがな – it forms the verb/adjective endings (which shows tense and the like), and also helps to indicate which of the kanji’s readings (usually the kun readings) is being invoked (for example: 出る = でる while 出す = だす).

If you just want to write a kanji on its own without the okurigana popping up, generally you’ll use the on reading (which in this case is しゅう), though this is a little trickier, since on readings tend to be shared between several characters – it’s simpler just to write the kun reading and delete the okurigana. In real usage, you’d type whole words, rather than kanji-by-kanji – that is, when you want to write (say) 収入, you’ll just write しゅうにゅう, not おさめる-delete-delete-はいる-delete.

Just idly, what exactly are you trying to do?