Sometimes removing an rpm isn't practical, particularly if there are other programs on the system that depend on it. For example, you might have installed an "x-amusements" rpm which lists Xsnow as a dependency, so using rpm -e to remove Xsnow is disallowed:

# rpm -e xsnow
error: removing these packages would break dependencies:
        /usr/X11R6/bin/xsnow is needed by x-amusements-1.0-1

In that case, you could re-install Xsnow using the --force option:

# rpm -ivh --force xsnow-1.41-1.i386.rpm
xsnow                       ##################################################