Remove wrong/faulty "default" comment from cli options

freqtrade/commands/cli_options.py

@@ -450,8 +450,7 @@ AVAILABLE_CLI_OPTIONS = {
     ),
     "exchange": Arg(
         '--exchange',
-        help=f'Exchange name (default: `{constants.DEFAULT_EXCHANGE}`). '
+        help='Exchange name. Only valid if no config is provided.',
-        f'Only valid if no config is provided.',
     ),
     "timeframes": Arg(
         '-t', '--timeframes',

freqtrade/constants.py

@@ -10,7 +10,6 @@ from freqtrade.enums import CandleType, PriceType, RPCMessageType
 
 DOCS_LINK = "https://www.freqtrade.io/en/stable"
 DEFAULT_CONFIG = 'config.json'
-DEFAULT_EXCHANGE = 'bittrex'
 PROCESS_THROTTLE_SECS = 5  # sec
 HYPEROPT_EPOCH = 100  # epochs
 RETRY_TIMEOUT = 30  # sec