How to - Delete a Custom Format in the Import Wizard

With the File->Import Wizard, you can create a custom.format file. The file is saved in the amibroker\formats folder.
How can this format be removed?

Go to Formats subfolder and edit import.types file. See the last paragraph of KB article:
http://www.amibroker.com/kb/2016/01/23/how-to-create-custom-import-definition-for-ascii-importer/