In RDM defining a column to ‘CHANGE_TYPE”, it actually means that an action (new, edited, deleted) on the record can be performed.
In order to be able to delete particular existing published record, in the source data a new column “CHANGE_TYPE” of type String should be created. After that, you should fill-in the column with value “DELETED” for those records that you would like to delete.
In addition, execute select query in your Database for <table_name>E (internal table for edited mode) and check how is specified column “ac_edit_state”. It is important to verify what exactly is the name of this table in your database, because it will be needed for the mapping in RDM importer step.
After that in RDM importer step you should do the mapping, see:
Another possibility is to disable incremental mode in the RDM importer step, then when you perform the plan, only the records, which are imported, are being updated. All the records missing in the import data are deleted. Please note that if you execute a plan from an empty file it would delete all records.