I've had problems with the suggested rm -r because it will follow symbolic links out to other filesystems. Imagine what fun we had when we ran that from /opt/BOB/new only to find that there was a link to /usr/lib contained within it. Yes, it went off an cleared that too. Good thing we didn't have a link to /dev, /usr or /.
If you have few enough files, you could:-
for object in *
do
if [ -f $object ]
then
rm $object
fi
done
This tests that the item is a file. It will not traverse down directories though. Do you want to do that too, or does the above suffice?
If you have lots of files, then you may have to write a stronger loop. We can get to that if you need it.