osx find exec rm find: exec: unknown primary or operator

It should be:

find . -name "*-e" -exec rm '{}' \;

Or better:

find . -name "*-e" -exec rm '{}' +

As per man find:

-exec utility [argument ...] {} +
   Same as -exec, except that ``{}'' is replaced with as many pathnames as possible for 
   each invocation of utility. This behaviour is similar to that of xargs(1).