class Mime::Type

def unregister(symbol)

Mime::Type.unregister(:mobile)

To unregister a MIME type:

This method is opposite of register method.

def unregister(symbol)
  symbol = symbol.downcase
  if mime = Mime[symbol]
    SET.delete_if { |v| v.eql?(mime) }
    LOOKUP.delete_if { |_, v| v.eql?(mime) }
    EXTENSION_LOOKUP.delete_if { |_, v| v.eql?(mime) }
  end
end