Not sure if it's best practice, but Domo is adding the commas since it's formatted as a number. Quick way to fix this is to make a beast mode that is Concat(`numberfield`) and then Domo will view it as Text.
Sometimes I've had to do Concat(`numberfield`, '') and add a space too.
One thing to look out for though is that converting the number to a text field will cause Domo to sort it based on the textual representation and not the numeric number within the field.
For Example (text sorting):
The way to get around the textual sorting issue would be to left pad your numbers with 0s which just causes another display issue of having leading 0s.