You can trim it with a pocket knife, exacto knife, dremel, file, sandpaper, etc.

You can dump the spinner and use a "prop hub" or "spinner nut" instead. There are several styles. Here's what Tower stocks; there are probably many others available but this list was easy to pull together.

If the plane does not "need" a spinner I prefer the hubs or nuts.

Dubro
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=DUB

Goldberg
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=GBG

Great Planes
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=GPM

Higley
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=HIG

OS
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=OSM

Tru-Turn
http://www2.towerhobbies.com/cgi-bin...p?&C=QKC&V=TRU


edited for spelling