Replication with only update and insert
If you're just going to delete this extra data manually on the odd occasion, you can simply turn off the binary logging for the current session. On the MySQL prompt run the following:

set sql_log_bin=0;

Then any query you enter won't be sent to the binary log, and thus won't be sent across to the slaves.

Once you're finished, re-activate binary logging with 

set sql_log_bin=1;

Reference: MySQL manual