As a dataset manager, you can specify a list of file-names that should be excluded from the published version of the dataset. Files with names that match one of the lines in the 'ignore'-list are excluded by the publishing workflow and will not be available through Blackfynn Discover.
You can find the option to create the ignore-list in the dataset settings page. Provide a single filename per line in the textbox. The ignore list does not support wildcards and you will need to include the full filename including the extension.